Program

Siding Spring Observatory is home to the 3.9m AAT, the ANU 2.3m, the UK Schmidt Telescope, and SkyMapper. It also hosts telescopes from eight organisations, a number that is likely to grow in the years to come. In this talk, we examine the role of Siding Spring in the context of Australia’s strategic partnership with ESO, the start of LSST in the early 2020s, multi-messenger astronomy and the era of ELTs.

On July 1, 2018 the AAT transitioned into a new governance and operational model, with its handover from the AAO to the AAT Consortium. This group of Australian Universities is now funding the AAT and governing its operations through the AAT Council, managing its operations through Astronomy Australian Limited, with telescope operations being run (under contract) by the ANU. This has necessitated a few changes to the model we have all been used to for the AAT, and will require further evolution in the years ahead.

With excavation of the of the telescope pier and enclosure foundations now complete, GMT is well on its way to delivering ELT access to the Australia community. I will present resent development highlights for the project and map out the evolving capabilities of the telescope as developed for the recently refreshed scientific vision driving the observatory.

Australia is a partner in the Maunakea Spectroscopic Explorer (MSE), a massively multiplexed spectroscopic survey facility that will be built in the coming decade on the Canada-France-Hawaii telescope site on Maunakea, Hawaii. MSE will be a dedicated, 11.25 m, wide-field telescope that will observe more than 4000 targets distributed over 1.5 square degrees in every pointing. MSE will use 8 fibre-fed spectrographs to capture ~3000 low resolution spectra (R~3000) and ~1000 high-resolution spectra (R~40,000) covering the full 1.5 sq. degree field contiguously with each resolution. MSE will have a survey speed that is ~6x faster than PFS and ~20X faster than MOONS based on aperture size x field of view x multiplexing x observing time. Furthermore, it will produce the same number of spectra as the full SDSS Legacy Survey every 7 weeks. Some of the initial science goals will be to identify the astrophysical location and details of stellar nucleosynthesis; unveil the composition and dynamics of the faint universe through chemical abundance studies of stars in the outer Galaxy; measure the masses of thousands of black holes at the cores of galaxies; weigh neutrinos; and test exotic models of cosmology where dark energy properties vary at high redshift. Australian scientists make up approximately 10 % of the MSE Science Team that now involves close to 400 astronomers from 30 countries. Furthermore, Australia has been picked to develop the fibre positioner system based on the systems AAO produced for Subaru and 4Most. Here, I will review the technical aspects of the facility and discuss scientific potential of the only dedicated 10-meter class spectroscopic facility planned for the coming decade.

A number of important milestones have been passed in the last 12 months, with the signing of the SKA treaty to establish the Square Kilometre Array Observatory (SKAO), the passage of design consortia through their Critical Design Reviews, and progress in the SKA Science Working Groups and Focus Groups. This talk will include updates from the Australian SKA Office (part of DIIS), the Australia--New Zealand SKA Coordination Committee, and the Science Working Groups to keep the community informed of progress towards construction of this transformational telescope.

As SKA-Low moves towards the construction phase, several prototype/verification stations have been deployed including the Aperture Array Verification Systems and the Engineering Development Arrays. The stations consist of 256 dipole antennas in a 35-40 metre diameter area, and have been undertaking verification and limited science observations. This presentation will give an overview of the design and performance characteristics of the stations, and the road to SKA-Low.

The Murchison Radio-astronomy Observatory (MRO) is located in an extremely radio quiet region of the planet, approximately 800 kilometres north of Perth, within the boundaries of the Boolardy Station pastoral lease. This unique observatory is now the most well protected radio astronomy site in the world. The MRO is currently the site of the Australian Square Kilometre Array Pathfinder (ASKAP), operating over the frequency range 700 – 1800 MHz, the Murchison Widefield Array (MWA), operating over 50 – 350 MHz, and EDGES, observing between approximately 50 – 200 MHz. The Australian component of the international Square Kilometre Array (SKA) telescope project is also to be sited in the same region. The extremely remote nature of this location makes it an ideal site for radio astronomy. Since 2005, a number of regulatory measures have been introduced by the Commonwealth government (through the Australian Communications and Media Authority) and the Western Australian government (through the Department of Mines, Industry Regulation and Safety) to prevent or control radio frequency interference (RFI) to radio astronomy at the MRO. In total, these measures provide unprecedented radio quiet protection – in frequency coverage, in geographic extent, and in the range of potential interference sources. The protections in place cover the frequency range 70 MHz to 25.25 GHz, an area 260 km in radius, and address both intentional radiocommunication transmitters and incidental emissions from electrical equipment. The best way to demonstrate the success (or failure) of these radio quiet measures is to use the radio telescopes themselves. The success was shown in 2018 when EDGES announced possible evidence of an indirect detection of signals from the birth of the first stars, in the “cosmic dawn” era, which would not have been possible without the excellent radio quiet environment at the MRO. The presentation will include more recent RFI measurements at the site using improved monitoring equipment as well as data from the MWA and ASKAP telescopes which show the very low RFI achieved. A brief description and explanation of the radio quiet protection will also be presented.

Gravitational waves from coalescing neutron stars encode information about nuclear matter at extreme densities, inaccessible by laboratory experiments. The late inspiral is influenced by the presence of tides, which depend on the neutron star equation of state. Neutron star mergers are expected to produce remnant hyper-massive (and/or supra-massive) neutron stars. These rapidly rotating remnants emit gravitational waves, providing clues to the hot post-merger environment—a likely source for r-process elements. The signature of nuclear matter in gravitational waves becomes most important at frequencies of 2-4 kHz, outside of the most sensitive band of current detectors. We present the design concept and science case for OzHF, a gravitational-wave detector optimised to study nuclear physics with merging neutron stars. The OzHF concept uses high laser power along with quantum squeezing in order to achieve the sensitivity necessary to probe nuclear matter using high-frequency gravitational waves.

The Pierre Auger Observatory has been fully operational since 2008. In that time, it has continued to be the pre-eminent ultra high energy astrophysical observatory, recording and measuring cosmic rays (UHECR) having energies up to ~10^20 eV with unprecedented precision, and setting important upper limits to the fluxes of photons and neutrinos above 10^18 eV. The Observatory is continuing to map cosmic ray arrivals and will soon be enhanced with a significant upgrade to enable it to estimate the mass composition of all the recorded particles. At the highest energies accessible to Auger, the highest particle energies known to exist, deflections of cosmic ray nuclei in passing through the galactic magnetic field become sufficiently small that it has become possible to map the sky in charged cosmic rays. The current results of that mapping, and discussion of its limitations and future prospects with improved composition data, will be presented.

The last two decades have seen an immense growth in our understanding of the physics of the birth and evolution of our Universe. However there are still many unanswered questions relating the nature of the dark energy and gravity on large-scales. In order to investigate these problems, upcoming wide area surveys in the radio and optical will measure the baryon acoustic oscillation standard rulers and redshift-space distortion growth rate of structure. In this talk we discuss the cross-correlation of two such surveys: TIANLAI, a large-area survey of neutral hydrogen in the radio, and DESI, an optical galaxy redshift survey. By cross-correlating the two, the science will be enhanced while systematic errors are mitigate. We show results made using the Horizon Run 4 cosmological N-body simulation.

In this talk I review attempts to build a self-consistent model for the dynamical state of the ISM in star-forming galactic discs. Ideally such a model would incorporate star formation, stellar feedback, gravitational instability, the maintenance of turbulence, and perhaps the transport of gas through the ISM, into a unified framework, simultaneously explaining the relation between gas content and star formation (the Kennicutt relation), the observed correlation between galaxies' star formation rates and velocity dispersions, and a variety of other observations. I summarise the various ways that theorists have attempted to fit together physical ingredients to reach this goal, the differing physical pictures behind these models, and the strengths and weaknesses of each when it comes to reproducing the observations. I then show that it is possible to combine the best elements of these models into a single, unified picture that successfully reproduces most of the major observations. I suggest future observations and numerical experiments that can be used to test this unified model.

The detection of the 21cm neutral hydrogen signal from the Epoch of Reionisation is an ongoing goal for international radio astronomy teams, but progress has been hampered by the complexity of the instrumentation and the bright foreground sky obscuring the signal. In this talk I will briefly review two new methods that attempt to detect signals from this early period of the Universe using data from the Murchison Widefield Array. First, we use a kernel density estimator to study the distribution of the data, and show that we are able to discriminate foregrounds from signal more easily than the typical power spectrum. Second, we attempt the first observational measurement of the 21cm bispectrum, the Fourier Transform of the three-point correlation function. We show that this is a promising technique for current radio interferometer experiments. Reference 1: Trott, Fu, Line, Murray, Jordan, et al, MNRAS, accepted, 2019; Reference 2: Trott, Watkinson, et al, PASA, accepted, 2019

Fast Radio Bursts (FRBs) are one of the great mysteries of modern astronomy. The fact that these millisecond bursts of radio emission remain detectable across cosmological distances implies a hitherto-unknown and incredibly energetic emission mechanism. Beyond the tantalizing prospect of discovering their origins, these bursts also encode information about all the ionised plasma encountered along their lines of sight and thus promise to be highly valuable cosmological probes. The key to unlocking both of these applications is associating FRBs with their host galaxies -- a task requiring arcsecond precision localisations. In this talk I will present the results of searches for FRBs with the Australian Square Kilometre Array Pathfinder (ASKAP), which -- with its 6-km maximum baseline -- has achieved FRB localisations with (sub-)arcsecond precision. I will discuss the FRBs localised to date by ASKAP along with the method used to pinpoint their origins, before briefly summarising what these FRBs have revealed about the potential progenitors and hosts.

Despite the progress in our computational abilities, combining detailed stellar evolution with codes for modelling clusters and galaxies still remains a challenge. A less accurate but simpler way to achieve the same is the method of defining polynomial fits to the stellar evolution tracks, developed by Hurley et al in 2000. It has been a popular choice for population synthesis codes for over two decades but the developments in stellar physics, especially for massive stars, have created a pressing need to update them. However, these formulae are not only hard to define but are also less adaptable to changes in stellar tracks. Hence, in this work, we present results from an alternative approach, based on numerical interpolation of the stellar tracks. It's comparable to the earlier method in terms of speed and accuracy. It is also highly flexible and can be used with a variety of stellar evolution outputs.

The free electron column density is a direct measurement of the ionisation state of the IGM. We have used the EAGLE simulations to create free electron column density distribution maps between redshifts 0 < z < 3. From these column density distribution maps we have estimated a new dispersion measure – redshift relation for fast radio bursts (FRBs). Since the frequency dispersion (dispersion measure) of a FRB signal is cause by free electron interactions along the line of sight, we should be able to use FRBs to directly probe the ionisation state of the IGM at low redshifts (z < 3). This dispersion measure-redshift relation will be made published in a new python package that I developed called Fruitbat.

The CTA telescopes are designed to detect the Cherenkov light produced by TeV air showers. Using the morphology formed by the triggered pixels, air showers initiated by gamma rays are identified. We propose to use the CTA telescopes to observe the fluorescence light produced by air showers to constraint high energy particle interaction properties (beyond the LHC energy range) and to extend to higher energies the CTA energy range.  In contrast with the Cherenkov light produced in air showers, which is mainly emitted in the direction of the air shower, the fluorescence light is emitted isotropically and can be detected from further away (increasing the detector collecting area). Another useful characteristic of the fluorescence  light is that the intensity of the observed fluorescence light is  proportional to the number of charged particles in the direction of the  corresponding pixel. These two properties make fluorescence detectors ideal  for the detection of high energy air showers (beyond PeV).  Existing high  energy fluorescence detectors have pixel angular sizes larger than 1deg, but  the CTA telescope have pixel angular sizes of  only 0.17deg.  These  extraordinary CTA angular resolution is the main driving of this project. We  propose that CTA telescopes might be able to measure the lateral  distribution function (LDF) of high energy air showers at different  atmospheric depths. The measurements of the LDF at different atmospheric  depths (for a given shower) has not been done in the past and it would allow  to constrain the high energy particle interaction properties used by  different air shower simulation models. Furthermore, measurements of the LDF  at different slant depths might allow the discrimination between air showers  initiated by gamma rays or by cosmic rays. Which would allow to extend to  higher energies the CTA energy range for gamma ray detection.

Two examples of many anticipated studies using the Mopra Central Molecular Zone (CMZ) Carbon Monoxide (CO) data are presented. Data from both the original CMZ region and an extension towards 358 degrees Galactic Longitude are utilised. First, comparisons are made between the molecular gas data and a Very High Energy gamma-ray source detected by HESS, the PeVatron candidate HESS J1741-302. Second, a method for using lower abundance isotopologue lines of CO to correct for optical thickness in their more abundant counterparts is tested on the molecular cloud Sagittarius B2.

As stars ascend the red giant branch, their surface abundances of carbon and lithium are depleted. This is indicative of an internal mixing mechanism, which is modelled variously as thermohaline mixing, meridional circulation and as a result of magnetic fields. The depletion rate is observed to be higher in low metallicity stars, and models predict that the mixing is also stronger in low mass stars. The second APOKASC catalogue contains 6676 evolved stars with APOGEE spectroscopic parameters and Kepler asteroseismic data, which can be used to derive the mass, radius and age of these stars. With this data we can carefully examine the depletion with respect to metallicity and stellar mass, including the predicted mixing cutoff at 2.2 Solar masses, which is predicted by the models, but has not been conclusively demonstrated observationally.

USQ provides a significant regional Queensland capability in astronomical and space sciences via a comprehensive astronomy distance education program, highly rated stellar and planetary systems research, High Performance Computing numerical simulations, and development of Mt Kent Observatory as Queensland’s only professional astronomical and space sciences observatory. Over the past decade Mt Kent has hosted remote-access imaging telescopes for the Shared Skies Partnership with the University of Louisville, and in 2018 MINERVA-Australis was commissioned on the site as a robotic telescope array and spectrograph dedicated to exoplanet radial velocity observations supporting the NASA Transiting Exoplanet Survey Satellite mission. Forthcoming site facilities for 2019 comprise a Stellar Observations Network Group (SONG) telescope array node and spectrograph for astroseismology, a DLR SMARTnet space debris monitoring telescope, and an Australian Desert Fireball Network meteor camera. Looking further ahead, Mt Kent Observatory is expected to provide ground-based observing support for the UK-led “Twinkle” exoplanet atmosphere and Solar System spectroscopy space telescope launching in 2022. Mt Kent Observatory’s future aligns with an increasing USQ focus on space science and engineering.

One of the key targets for continuous gravitational wave (GW) searches is the low mass X-ray binary (LMXB) Scorpius X-1. We report on a search for GWs from Sco X-1 in data from the second observing run of the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO). LMXBs are an interesting class of targets because their X-ray luminosity allows us to set an indirect upper limit on GW strain amplitude, which approaches LIGO's current sensitivity. Sco X-1 is a particularly interesting target because it is the brightest LMXB. This search uses a hidden Markov model (HMM) to account for unpredictable stochastic variations in GW emission frequency, and builds on previous HMM-based searches by using a more sensitive detection statistic.

We investigate the relationship between the black hole accretion rate (BHAR) and star formation rate (SFR) for Milky Way and Andromeda-mass progenitors from z = 0.2 to 2.5. As the progenitors evolve, their relative black hole-galaxy growth rate (BHAR/SFR) increases from low to high redshift. This result contrasts previous studies, which tend to find an almost flat slope and is likely due to their use of a broad mixture of galaxies with different evolutionary histories.

I will discus the importance of pre-processing of galaxies in groups as they fall into clusters. In particular, I will present the galaxy ESO156-G029, which is a member of a galaxy group which is positioned at the virial radius of the cluster Abell 3193. I will show that ESO156-G029 has disturbed kinematics and a highly asymmetric neutral hydrogen distribution, which are consequences of group pre-processing, and possibly of an early phase of ram-pressure stripping. Finally, I will suggest a scenario in which ESO156-G029 has had a gas-rich merger in the past and has now started to experience ram-pressure stripping which will eventually result in removal of gas from the galaxy. Finding more of such cases is important in order to determine how much are gas-rich galaxies (from the group environment) contributing to the overall build-up of galaxy clusters.

The dark energy plus cold dark matter (ΛCDM) is the most favoured theory for describing the Universe. However, there are some differences between the theory and what has been observed. As an example, cosmological simulations predict that the number of dwarf satellite galaxies is much more than what we have observed so far. This so-called Missing Satellites problem might be resolved by searching for very diffuse dwarf galaxies that might have been missed using conventional telescope searches. Nevertheless, the improvement in faint objects observation has speeded up recently. Some aspects of this progress applied to the Huntsman Telescope project. To reduce internally scattered light, the Huntsman Telescope uses canon lenses instead of mirrors.

The main goal of the Huntsman Telescope is specifically to observe extremely diffuse astronomical objects. By cataloging the number diffuse dwarf galaxies we can help constrain the cosmological parameters of the universe. To properly compare our search results with simulations, we need to create “mock images” of the simulation output. These mock images take simulated galaxies and mimic the impact of the telescope system to produce realistic looking imaging data. The main steps for producing Huntsman Telescope mock images are presented in this work

KM3NeT is a multi-site undersea research infrastructure in the Mediterranean for the detection of neutrinos in the 3 GeV to 10 PeV range. The Mediterranean location means maximum sensitivity for neutrinos coming from the southern hemisphere. In Phase 2, 2/3 of the research infrastructure (the `ARCA' detector') will be deployed off the coast of Sicily to target the 100 GeV to 1 PeV range, in order to discover and subsequently observe sources of high-energy neutrinos in the Universe. This goal is motivated by observation of a high-energy astrophysical neutrino flux of unknown origin by IceCube, and the plethora of potential sites of particle acceleration in the universe identified by astronomical observations from radio to gamma rays. These include Galactic sources such as supernova remnants, pulsar wind nebulae, Sgr A* (which may be the Galactic centre Pevatron), the Fermi Bubbles, and cosmic ray secondaries from interactions in molecular clouds; and extragalactic sources such as different classes of AGN, star-forming galaxies, GRBs and a cosmic diffuse component. While having an instrumented volume only slightly larger than IceCube's, the key feature of the KM3NeT/ARCA detector is its improved angular resolution, allowing source identification. There is mutual benefit from closer involvement between KM3NeT and the Australian astronomy community and note that some members of the KM3NeT consortia have already established strong links with Australian facilities and projects, including the Murchison Widefield Array (MWA).

Compact massive galaxies with effective radius smaller than 2kpc and stellar mass of around 10^11 solar mass are observed in large quantity at high redshift. Locally however, such objects are non-existent and galaxy tends to be larger in size. One potential explanation is that the compact spheroid accreted gas to become modern day disc-shaped galaxies. In this project, a volume limited sample of galaxies in the local universe is selected. We conducted a detailed brightness profile decomposition beyond the standard bulge-disc fit, while also considering the influence by other structures like Bars, rings and etc. Hence the size and mass of the bulge will be accurately modeled. We intended to compare the number density of the compact bulge and the high-z spheroid in order to constraint galaxy formation scenarios.

The observational follow-up campaign of the gravitational wave (GW) multi-messenger event GW170817/GRB170817A showed that the prompt $\gamma$-rays are consistent with a relativistic structured jet observed from a wide viewing angle $\gtrsim 20$\deg. We perform Bayesian inference using the data from early and late EM observations of this event to determine the jet profile of GRB170817A assuming a structured jet model. The geometric dependence on the burst luminosity allows one to produce a short duration gamma-ray burst (sGRB) efficiency function with redshift for Fermi-GBM, which folded in with binary neutron star detection rate, yields estimates for the future joint GW/sGRB detection rates for LIGO and Virgo detectors. Our results show that, if the jet structured profile of GRB170817A is a relatively common feature of sGRBs, then there is a realistic probability of another off-axis coincident detection during the current third aLIGO/Virgo observing run (O3); we assess this prediction based on detections during the current run. Looking forward, we find that up to 4 yr$^{-1}$ joint events may be observed during the advanced LIGO run at design sensitivity (2021-) and up to 10 yr$^{-1}$ during an upgraded advanced LIGO configuration A+ (2024-). We show that the detection efficiencies for wide-angled sGRB emissions will be limited by GRB satellites as the GW detection range increases through proposed upgrades. Therefore, although the number of coincident detections will increase with GW detector sensitivity, the relative proportion of detected binary neutron stars with $\gamma$-ray counterparts will decrease; 11\% for O3 down to 2\% during A+ [1]. [1] E. Howell, K. Ackley, A. Rowlinson, D. Coward, \emph{Joint gravitational wave - gamma-ray burst detection rates in the aftermath of GW170817}, 2019, MNRAS, 485, 1435

The elastic crust of a neutron star deforms as it spins down. This leads to a non-zero quadrupole moment causing the emission of gravitational waves. Here we present an idealized model of crust dynamics including mechanical failure during the deformation process. The model is based on a cellular automaton with a nearest neighbor interaction and includes geometric effects. We predict the quadrupole moment and hence the gravitational wave strain for Galactic isolated neutron stars and discuss their detectability with the Laser Interferometry Gravitational-wave Observatory (LIGO).

Neutron star glitches -- sudden, impulsive increases in the spin frequency -- are thought to be the caused by the dynamics of superfluid vortices in the stellar interior. We present quantum mechanical simulations of collective vortex motion and evidence of glitches in a neutron star where the nuclear properties are stratified.

We observed the Spitzer-South Pole Telescope deep field (SSDF) for the diffuse source complement to O'Brien (2015) which surveyed 86 deg^2 of the SSDF for Bent-Tail galaxies, with an aim to survey galaxy clusters and their haloes. We used the Australia Telescope Compact Array (ATCA) and Australian Square Kilometer Array Pathfinder (ASKAP) to map the SSDF at 2100 and 864.5 MHz frequencies, respectively. Spectral decay at 2.1 GHz and sensitivity with 16 ASKAP antennas proved very difficult to detect halo emission, on top of their already low luminosity. Instead, this paper aims to catalogue and cross-match the compact sources between these two bands. We observe 8,211 ASKAP sources and 3,955 ATCA sources, of which 2,364 sources successfully cross-match between the two, after self-matching and careful flagging by eye. We analyze the known Brighest Cluster Galaxies (BCGs) in the region and find only 5 which match sources in our field, out of ~90 from various Optical and X-Ray catalogues. We find 30 sources which match, with tight 5" search radii, existing cluster catalogues in the field which suggest that they could be new BCGs.

With the rapidly increasing number of compact binary mergers detected by Advanced LIGO and Advanced Virgo instruments, the era of gravitational-wave astronomy is fully upon us. One of the next frontiers of GW astrophysics is the detection and characterisation of signals from rapidly rotating neutron stars. In this poster we present a joint hidden Markov model-based search for pulsations in X-ray data and GW data, showing preliminary estimates of the improvement gains by searching both data sets together.

The GALAH (Galactic Archaeology with HERMES) survey being carried out at the Anglo-Australian Telescope aims to study the formation and evolution of the Milky Way. While the majority of GALAH targets are in the thin and thick disk, there are also halo stars in the dataset. A population of halo stars with globular cluster-like abundance patterns has been identified in recent literature, leading to a new perspective on globular clusters as important contributors to galactic halo assembly. I will describe an ongoing search in the GALAH survey for members of this population of escaped globular cluster stars.

Dust-corrected star formation rate estimates at high redshifts primarily rely on the Meurer (IRX) - β relation which is calibrated against local starburst galaxies. To investigate the applicability of this assumption for dust extinction at these redshifts, we utilise a semi-analytic galaxy formation model to interpret and leverage high-redshift UV observations. Our modelling provides self-consistent predictions on the infrared excess (IRX) - β relations and cosmic star formation rate density. We integrate the Charlot & Fall dust model into our Meraxes semi-analytic model, and propose three different parametrisations for the dust optical depths, linking them to star formation rate, dust-to-gas ratio and gas column density respectively. A Bayesian approach is employed in order to statistically calibrate model free parameters including star formation efficiency, mass loading factor, dust optical depths and reddening slope directly against UV luminosity functions and colour-magnitude relations at z ~ 4 - 7. The best-fit models show excellent agreement with observations of the luminosity function. We calculate IRX using energy balance arguments, and find that there is large intrinsic scatter in the IRX - β plane which is driven by the specific star formation rate. Additionally, we find that the difference among the (IRX) - β relations predicted for the three dust models suggests that estimates the dust-corrected star formation rate at z>5 using the Meurer (IRX) - β relation carry a systematic uncertainty of at least a factor of 2 .

The majority of well-known radio active galactic nuclei (AGNs) are adorned with radio lobes that extend far beyond the core of the optical host galaxy. Despite significant advances in understanding the origins of such AGN, many questions remain about their evolutionary scenario. A subset of powerful, compact radio AGNs, which have the same morphology as the massive radio AGN but on much smaller spatial scales, seem to be the key to understanding the early evolutionary stages of radio AGN. However, it is still unclear whether these compact peaked-spectrum sources, identified due to their peak in their spectra, are small due to a dense surrounding environment (frustration scenario) or are young and have had insufficient time to grow to larger scales (youth scenario). The GaLactic and Extragalactic All Sky MWA (GLEAM) survey is unparalleled in finding these sources due to incredibly wide fractional bandwidth at low frequencies, with observations from 72-231MHz. A sample of 1,483 peaked sources from GLEAM was selected by Callingham et. al (2017). We have followed these sources up a year later with the MWA and conducted a variability analysis of their spectra - making this the largest spectral variability study of its kind. Contrary to expectations, we have found several sources that show significant variation in flux density and spectral shape. Such variation suggests that the population of peaked-spectrum sources at low frequencies also have a significant component of core-jet sources and highlights the difficultly of conducting a population analysis with a inhomogeneous sample.

Ultra-Compact Dwarf galaxies (UCDs) are intermediate objects between star clusters and galaxies. One theory of UCD formation is that they are the stripped nuclei of dwarf galaxies that were tidally disrupted by mergers with other galaxies. Recent observations have detected supermassive black holes in a few massive UCDs, supporting this formation hypothesis. However previous simulations have not had the resolution to model the presence of UCDs and their black holes. We have used the state-of-the-art EAGLE simulation to model the formation of UCDs. We have done this by tracking the most bound particles of galaxies that are stripped in the simulation, which we then identify as UCDs. The EAGLE simulation allows us to determine the size of the black hole that was in the progenitor galaxy and now resides in the surviving UCD. We first tested the radial distribution and masses of the simulated stripped nuclei against observed UCDs and found them to be consistent, suggesting that UCDs likely are stripped nuclei. Our next step will be to determine the black hole masses of the simulated stripped nuclei and compare them with observations. This will allow us to test the masses of the simulated UCD black holes against observed UCDs. In my talk, I will discuss UCDs and the simulation in greater detail, highlight some of our results and discuss future work to be done.

With the latest generation of galaxy surveys capable of detecting galaxies with stellar masses of down to 10$^{7.7}$ M$_{\odot}$, it is crucial that the prescriptions used by Semi-Analytic Model (SAM) to model smaller galaxies, especially satellites, has greater accuracy and better match observations. In particular, it is common practice for SAMs to use a simplified treatment of satellite mergers. Orbital analysis is a potential technique to investigate the validity of these prescriptions. I present a revised study of orbital properties, tidal mass loss and mergers using a new analysis tool, OrbWeaver that is available on Github. I use the merger trees extracted using state-of-the-art phase-space halo finder and merger tree builder (VELOCIraptor & TreeFrog) and several large N-body simulation from the GENESIS simulation suite to reconstruct the orbits of satellites. I find the orbital evolution in the eccentricity and period of satellites depends on the initial mass ratio and circularity. I also show merger timescale predictions used by SAMs overpredicts the merger timescale of small satellites as it ignores tidal mass loss.

The large-scale distribution of galaxies can be explained fairly simply by assuming i) all galaxies are hosted by halos and ii) a cosmological model. This simple framework, called the 'halo-model', has been remarkably successful at reproducing the large-scale clustering of galaxies observed in various galaxy redshift surveys. However, none of these studies have truly tested the 'halo-model' by carefully modeling the systematics. We present the results from a fully-numerical, accurate 'halo-model' framework and show that the theory can not simultaneously reproduce the galaxy projected correlation function and the group multiplicity function in the SDSS main samples. In particular, the bright galaxy sample shows significant tension with theory. We discuss the implications of our findings, as well as how to constrain different aspects of galaxy formation by simultaneously fitting multiple statistics.

Fundamentally, galaxies consist of different components with different physics. The two most significant components could be considered as disk and bulge. Having different studies we know that the dynamic, star formation, kinematic and stellar population in these two components are different. So the question is what physical processes and evolutionary history have leaded galaxy components to the shape we observe today? By structural decomposition of galaxies over a high dynamic range in both redshift and stellar mass, I investigate how the most resolved imaging data from the Hubble Space Telescope in COSMOS/DEVILS field can help us to disentangle galaxies into their components and study the evolution of mass and size of the components. This will tell us how the components of galaxies assemble their mass and how they relate to their size. Such a mass and size exploration of the components of galaxies might reveal how/why we see a heterogeneous population of galaxies having at least two very disparate ingredients.

All HI surveys are affected by selection effects, which in some cases can be quite complex. To understand these biases and how they affect our understanding of how galaxies populate dark matter halos, we have modelled HI emission lines of the galaxies in the semi-analytic model of galaxy formation SHARK, built on the LCDM SURFS suite of N-body simulations. We use the latter to create a mock ALFALFA survey with the same selection function and instrumental effects as the real survey. We explored the long-standing problem of the over-production of low circular velocity galaxies, and found our simulated ALFALFA survey to reproduce the observed HI velocity width distribution very well; hence, concluding that the discrepancies previously reported are due to the complex selection effects of HI surveys. We also found that these biases affect galaxies even at the dwarf galaxy regime. During this talk, I will present these results, and also show which biases might affect the upcoming HI surveys like WALLABY and DINGO, and how best to tackle them.

Gravitational-wave memory is a strong field effect of general relativity that manifests as a permanent displacement in spacetime after a gravitational wave has passed. I present our ongoing efforts to detect gravitational-wave memory with the LIGO/Virgo network. Although the signal is expected to be extremely weak, I show how the Bayesian Inference software ‘Bilby’ can be used to detect memory. Using a simulated population of binary black hole detections in LIGO/Virgo based on our current best estimates, I show how long it will take in practice to detect memory. Furthermore, I present how far events in the first two LIGO/Virgo observation runs have brought us to a memory detection.

Gamma-ray astronomy may offer answers to a long-standing question of high energy astrophysics: Where do cosmic rays come from? The gamma-ray emission seen from some middle-aged supernova remnants is now known to be from distant populations of cosmic-rays interacting with gas, but there is still much work to be done in accounting for the Galactic cosmic-ray flux. I will present analyses of the interstellar medium gas surrounding young and middle-aged Galactic supernova remnants such as W28, RX J1713.7-3946, HESSJ1731-347, Vela Jr, HESS J1534-571 and others using data from the Mopra radio telescope. By making the connection between supernova remnant high energy emission and gas, as traced by molecules such as CO, CS and NH3, we can test the potential of these objects to accelerate hadrons beyond TeV energies.

The Australian Square Kilometer Array Pathfinder (ASKAP) has now discovered over 27 fast radio bursts (FRBs) in fly's-eye mode and interferometry mode. The temporal properties of FRBs such as dispersion, scattering and pulse profile reveals the effects of propagation through large columns of plasma. This provides an insight to the intergalactic medium and the dense media in the host galaxies. In this talk we present a detailed study focusing on the temporal properties of ASKAP FRBs. We present a study of the Fly’s-eye FRB population for any evidence of scattering or intrinsic temporal structures. We compare the Fly’s-eye FRBs with the published Parkes and CHIME FRBs and discuss the relation between scattering and dispersion measure/redshift. We also present the temporal structure of FRBs detected in interferometry mode with high time resolution and discuss how this helps with understanding the host environment of the burst.

The detection of the first neutron star merger, GW170817, heralded the dawn of a new era in multi-messenger astronomy. Observations of the radio lightcurve helped constrain merger parameters including the jet opening angle, the energetics of the merger and the circum-merger density. However, these observations alone were insufficient to distinguish between two competing models for the merger geometry - where a relativistic jet launched along the merger axis either successfully breaks out of the dense surrounding medium, or dissipates within it ("choked" jet or cocoon). The tension between these models was not resolved until observations using Very Long Baseline Interferometry detected superluminal motion, suggesting that the late-time emission was jet-dominated. In this talk I will discuss prospects for the detection of future events and how we can place constraints on merger geometry using VLBI and observations of interstellar scintillation. I show that while the late-time outflow structure can be constrained using VLBI observations to either directly image the outflow, or detect centroid motion produced by the presence of a jet, these observations are unable to be used to determine early-time behaviour. Instead we can place meaningful constraints on the early-time source size via the detection of interstellar scintillation from high-cadence multi-frequency observations.

The new Veloce spectrograph for the AAT aims to provide the AAT with an internationally competitive precision Doppler facility targeting the exoplanetary science of both transiting and non-transiting planets. It is also the first facility-class instrument at the AAT in over 2 decades to be almost totally externally funded (via the ARC LIEF scheme and University contributions). I will review the lessons learned from this new process for building instruments, and update the exoplanetary results emerging fro the combination of Veloce and the NASA TESS mission

The great stability of millisecond pulsar periods and the existence of pulsars in binary systems make possible a range of tests of theories of relativistic gravitation, in particular, Einstein’s general theory of relativity (GR). In this talk I will discuss new results from 15 years of timing the Double Pulsar, PSR J0737-3039A/B, using the Parkes, Green Bank and European radio telescopes. These have enabled measurement of six relativistic parameters, giving five independent tests of GR in strong gravitational fields. The most stringent of these are fully consistent with GR at a level of 0.01%. They have also revealed the effects of Lense-Thirring precession and gravitational light-bending leading to constraints on the moment of inertia of the neutron star.

R N Manchester¹, M Kramer², N Wex², I H Stairs³ and M Burgay⁴

1. CSIRO Astronomy and Space Science, Sydney, Australia
2. Max Planck Institute for Radio Astronomy, Bonn, Germany
3. University of British Columbia, Vancouver, Canada
4. Cagliari Astronomical Observatory, Cagliari, Italy

Bayesian parameter estimation is fast becoming the language of astrophysics. It is the method by which gravitational-wave data is used to infer the sources’ astrophysical properties. We introduce a user-friendly Bayesian inference library for gravitational-wave astronomy, Bilby. This python code provides expert-level parameter estimation infrastructure with straightforward syntax and tools that facilitate use by beginners. It allows users to perform accurate and reliable gravitational-wave parameter estimation on both real, freely available data from LIGO/Virgo and simulated data. Bilby is versatile enough to perform inference on any data set; I will present examples from radio pulsar observations, x-ray astronomy, and more.

With the latest LIGO/VIRGO observing run well underway, gravitational-wave detections are being recorded at a rate of roughly one a week. Some of these events are easier to detect than others. For example, it is easier to detect binaries with higher masses than lower masses. Detection efficiency depends on other variables as well including sky location, distance, and the orientation of the binaries. The non-uniformity of detection efficiency leads to selection effects, creating bias in astrophysical inferences. In this talk I discuss how selection effects impact a range of astrophysical inferences, from the sky maps sent to electromagnetic astronomers to binary masses. I describe how to fold selection effects into inference calculations in order to yield unbiased inferences.

Our analysis of 84 early-type galaxies (ETGs) with directly-measured super-massive black hole (SMBH) masses nearly doubles the number of such galaxies with multi-component photometric decompositions. We establish new robust scaling relations between the black hole mass and the host galaxy properties, including spheroid/bulge stellar mass, total galaxy stellar mass, central velocity dispersion, spheroid Sersic index, and spheroid half-light radius. We explore the scaling relations for various sub-populations of ETGs and discover intriguing results which also hold ramifications for formation theories, simulations, and specific virial factor measurements used to convert AGN virial masses into black hole masses. Combining our work with all 48 late-type galaxies (LTGs) having directly-measured SMBH masses, we provide a clear picture of how black hole mass scale in galaxies. Implications for predictions of long-wavelength gravitational wave detection by the Parkes Pulsar Timing Array, MeerKAT, and LISA will briefly be mentioned.

In the local Universe, the gravitational effects of mass density fluctuations exert perturbations on galaxies’ redshifts on top of Hubble’s Law, called ‘peculiar velocities’. These peculiar velocities provide an excellent way to test the cosmological model in the nearby Universe. In this talk, we present new cosmological constraints using peculiar velocities measured with the 2MASS Tully-Fisher survey (2MTF), 6dFGS peculiar-velocity survey (6dFGSv) and the cosmicflows-3 compilation. Firstly, the dipole and the quadrupole of the peculiar velocity field, commonly named ‘bulk flow’ and ‘shear’ respectively, enable us to test whether our cosmological model accurately describes the motion of galaxies in the nearby Universe. We develop and use a new Bayesian estimator that accurately preserves the error distribution of the measurements to measure these moments. In all cases, our results are consistent with the predictions of the Λ cold dark matter model. Additionally, measurements of the growth rate of structure, fσ8 in the low-redshift Universe allow us to test different gravitational models. We developed a new estimator of the “momentum” (density weighted peculiar velocity) power spectrum and use joint measurements of the galaxy density and momentum power spectra to place new constraints on the growth rate of structure from the combined 2MTF and 6dFGSv data. We recover a constraint of fσ8=0.404+0.082-0.081 at an effective redshift zeff=0.03. This measurement is also fully consistent with the expectations of General Relativity and the Λ Cold Dark Matter cosmological model. Finally, we discuss the implications for future peculiar velocity surveys (i.e., WALLABY, TAIPAN or from LSST) and how the new techniques we have developed could be used on these data to produce even more accurate tests of our cosmological model.

Galaxy clusters are among the largest structures in the Universe and form the highest peaks in the matter density on megaparsec scales, which makes them one of the most sensitive probes of the late time Universe. I will discuss the lensing of cosmic microwave background (CMB) radiation by galaxy clusters. CMB-cluster lensing is an especially valuable tool to constrain galaxy cluster masses at high redshifts. In particular, this talk will focus on a new method to incorporate the CMB lensing mass information into parameter constraints from galaxy cluster cosmology. The improved constraints from CMB lensing are expected to improve constraints on the Dark Energy equation of state $w$, the $rms$ value of amplitude fluctuations $\sigma_8$, and the total neutrino mass $\Sigma_\nu$.

The cosmic microwave background (CMB) anisotropies provide a snapshot of the universe at the time of recombination, and their accurate measurements have advanced our understanding of the origin, composition, and evolution of the universe. However, the path of CMB photons is gently deflected by the intervening large-scale structure (LSS), perturbing our view of the primordial universe. This effect, dubbed weak gravitational lensing, introduces non-Gaussian features in the observed CMB temperature and polarisation anisotropies which can be exploited by high-sensitivity experiments to reconstruct the projected mass distribution out to the surface of last scattering. Thus, CMB lensing offers a unique window on the dark universe by being sensitive to the geometry and growth of LSS, which in turn can place tight constraints on the sum of neutrino masses and on the mechanisms sourcing the cosmic acceleration. In this talk, I will present a new measurement of the CMB lensing potential power spectrum using data from 500 deg^2 of the southern sky observed with SPTpol, a millimeter-wavelength polarisation-sensitive receiver installed on the South Pole Telescope, and discuss its cosmological implications.

The All-Sky Virtual Observatory (ASVO) is enabling researchers to access data across a federated network of datasets, from all types of astronomical facilities in Australia. This talk is split into two sections. Firstly, we provide a short overview of the 5 nodes currently comprising the ASVO (SkyMapper, TAO, Data Central, MWA, CASDA) to re-familiarise astronomers with their current capabilities, as well as planned development going forward on a per-node basis. In the second half of this talk we present the future vision of the ASVO as a coordinated group of virtual observatories serving the astronomical community. We report on the planned interoperability between the nodes and compliancy with IVOA protocols, as informed by the community through the 2018 ASVO User Survey. Finally, we present possible use-cases for the planned future upgrades to the nodes, showcasing the scope of the scientific investigations that are possible with the ASVO.

Streams of stars from captured dwarf galaxies and dissolved globular clusters are identifiable through the similarity of their orbital parameters, a fact that remains true long after the streams have dispersed spatially. We calculate the integrals of motion for 44855 stars, out to a distance of four kiloparsecs, with full 6D phase space positions in the Gaia DR2 catalogue. We then apply a novel combination of data mining, numerical and statistical techniques to search for stellar streams. This process returns seven high-confidence streams (including four that were not known to exist) that display tight clustering in the integral of motion space. Colour-magnitude diagrams of the stars in each stream indicate that they are relatively simple, old, metal-poor populations with energy, angular momentum and eccentricity values that suggest they are captured dwarf galaxies. The success of this project demonstrates the advantages of using data mining techniques in exploring large survey data sets.

The Australian Dark Energy Survey (OzDES) completed its sixth and final year of observations this past December. As part of OzDES the Reverberation Mapping (RM) program regularly targeted 771 AGN out to a redshift of z < 4.5 with the goal of measuring black hole masses. With this data we will be able to verify the radius-luminosity relationship out to high redshifts, study black hole mass evolution, and test whether or not AGN can be used as standard candles in cosmology. I will overview the OzDES RM program and present the results obtained using the first five years of data.

Binaries of supermassive black holes at sub-parsec separations, which are thought to be natural products of galaxy mergers, have yet to be discovered. On the one hand, pulsar timing arrays provide a promising way of detecting the gravitational waves emitted by such systems. Many believe that such a breakthrough detection is likely to happen in the next few years. On the other hand, there have been hundreds of binary candidates reported in the last several years from electromagnetic surveys. For example, a large number of candidates have been claimed based on the apparent periodic variations in quasar light curves. However, the intrinsic stochastic variability of quasars, usually termed as red noise, can lead to false detections with the standard periodogram search, making such claims ambiguous. In this talk, I will first summarise multimessenger efforts to detect such binary black holes. Then I will describe a new detection technique that can unambiguously identify supermassive binary black hole candidates in quasar light curves. I will present my findings on several well-known candidates.

The HESS galactic plane survey (HGPS) has released a map of TeV gamma-ray sources with more than 70 observed candidates. Studying the origin of these TeV sources is critical to high energy astrophysics. While the optical band, especially in the H𝝰 emission line, its relationship to the HGPS has not previously been studied. The discovery of the optical SNR counterpart HESS J1825-137 in H𝝰 has guided our investigation of other TeV candidates with similar morphologies. We have looked for eleven HESS TeV sources and found three potentially interesting H𝝰 features that may be associated with the TeV emission.

One of the main challenges in modern astrophysics is to achieve a complete understanding of how galaxies evolve over time. The knowledge of a galaxy’s star formation history, both globally and in a resolved manner, provide key pieces of information for understanding galaxy formation and evolution. This evolution of star forming properties depends both on intrinsic properties as well as external influences from the surrounding environment. Recent results from the SAMI Galaxy Survey data reveal signatures of outside-in quenching which is prevalent in galaxies on their first passage through the core of a galaxy cluster. The evidence supports a scenario where ram pressure stripping (RPS) is removing gas from these galaxies as they traverse the cluster, leading to the quenching of star formation. We are using the KOALA integral field spectrograph on the Anglo-Australian Telescope (AAT) to follow up two of the SAMI galaxies which show evidence for recent quenching. KOALA provides a wider field of view of these galaxies when compared with the SAMI observations, allowing the search for signatures of environmental interaction which occur at large galactocentric distances, such as ionised tails of stripped gas. In this poster, I will present preliminary analyses of the emission line properties of these two galaxies, which will be used to search for further evidence of environmental stripping.

We apply Bayesian statistics to perform model selection on different reionisation scenarios via the Multinest algorithm. Initially, we recover the results shown by 21CMMC for the parameter estimation of 21cmFAST models. We proceed to test several toy models of the Epoch of Reionisation (EoR) defined in contrasting morphology and scale. We find that LOFAR observations are unlikely to allow model selection even with long integration times. HERA would require 61 dipoles to perform the same analysis in 1080 hours, and becomes comparable to the SKA with 217 dipoles. We find the SKA requires only 324 hours of observation to conclusively distinguish between our models. Once model selection is achievable, an analysis of observational priors is performed finding that neutral fraction checks at specific redshifts add little to no inference. We show the difficulties in model selection at the level of distinguishing fiducial parameters within a model or distinguishing galaxies with a constant versus power law mass-to-light ratio. Finally, we explore the use of the Savage-Dickey density ratio to show the redundancy of the parameter Rmfp within 21cmFAST.

Astrophysical jets are frequently observed phenomena in the Universe, ranging from high-energy jets in active galactic nuclei to low-energy stellar jets. In our recent studies, we have detected jets from a large fraction of binary post-AGB systems. The rich time-resolved optical spectroscopic data available for each of these post-AGB binaries with jets allows us to study the tomography of these jets. In Bollen et al., 2019, we have successfully developed a robust jet modelling code in order to determine the full spatio-kinematic structure of post-AGB binary jets. Jets from post-AGB binaries are diverse since these systems differ in terms of their orbital parameters and systems sizes. Therefore, in our on-going work, we apply our jet modelling code to the diverse sample of 15 jet-creating post-AGB binaries. Additionally, we also determine the mass accretion rates and jet outflow momenta, which give an insight into the changing conditions in the inflow and outflow that directly affect the launching of these jets and their environment. In this talk, I will present the results of our work which shed light on the nature of post-AGB binary jets and their launching mechanism.

The IceCube Neutrino Observatory located at the South Pole, Antarctica, is the world's largest neutrino telescope. IceCube consists of 86 strings instrumenting a cubic kilometre of Antarctic ice, with each string holding 60 digital optical modules for Cherenkov radiation detection. The detector was constructed between 2004 and 2010 with a primary goal of observing neutrinos from the highest energy processes in the Universe. In 2013, the IceCube Collaboration reported the first ever detection of an astrophysical neutrino flux, however no distinct sources were resolved. In September 2017, a high-energy neutrino alert from IceCube was followed up in real time by many other telescopes, revealing a gamma-ray flaring blazar in a high state of activity. This time coincidence strongly suggested a common origin of the neutrino and gamma rays from the source TXS 0506+056. Analysis of the historic neutrino data from this direction found evidence of a flare of neutrinos several years prior to this event. Together, these observations suggest that this blazar is the first identified neutrino source.

To further the capabilities of IceCube, the "IceCube Upgrade" will involve the deployment of 7 additional strings in the centre of the detector over the 2022-2023 summer season. This larger concentration of strings at the centre of the telescope will probe lower-energy neutrinos and help understand neutrino mass hierarchy and neutrino oscillations. Over the longer term, the hope is to construct IceCube-Gen2, which would expand the observatory to 10 cubic kilometres, add a large surface background shower veto array, together enhancing the all-sky observational capabilities of the observatory.

Since aLIGO/Virgo began their third observing (O3) run in April 2019, they keep detecting gravitational wave signals from new binary neutron star mergers. After the first event, GW170817, this is now the next opportunity to identify electromagnetic counterparts (kilonovae) and provide insights into long-standing questions about the physics of the merger process and the resulting nucleosynthesis. Here, we will present an overview of the SkyMapper follow-up program in O3, our infrastructure for real-time discovery and recent results of our searches for optical counterparts. Finally, we will discuss complex follow-up strategies in response to rapidly evolving situations driven by multi-messenger observation campaigns.

One of the important probes to understand the evolution and interaction processes of the the LMC & SMC is the estimation of their chemical composition and its spatial distribution. In previous works, we estimated first-of-their-kind metallicity maps for the inner regions of the LMC & SMC by combining large-area photometric (OGLE III and MCPS V and I bands) and spectroscopic data. The slope of the Red Giant Branch (RGB) is used as an indicator of the mean metallicity of a small region within the galaxy, and it is calibrated using spectroscopic data for field and cluster RGB stars. The VMC VISTA survey has observed a much larger area of the LMC & SMC than the MCPS and OGLE III surveys, covering inner as well as outer regions. In addition, the effects of reddening will be less important in near-infrared passbands compared with optical bands. Presently, we are employing our technique of metallicity estimation, using the Y and Ks photometric bands and VMC data, to construct near-infrared metallicity maps for the general field of the SMC. The resulting near-infrared metallicity map is expected to complement its optical counterpart. Details and initial results will be presented.

The Cherenkov Telescope Array is the next-generation observatory for ground- based gamma-ray astronomy. With more than 100 telescopes equipped with state- of-the-art technologies, it will provide a new view of the sky at energies between a few GeV and up to 300 TeV. This contribution will give an overview and status of the project and will inform about Australia’s involvement in the project. It will also present synergies between CTA and other areas.

In this talk, I will report the B-mode power spectrum measurement from the cosmic microwave background (CMB) polarization anisotropy observations made by the SPTpol instrument on the South Pole Telescope. This work expands the sky area to 500\,$\mathrm{deg}^2$, a five-fold increase over the last SPTpol B-mode release. As a result, the bandpower uncertainties have been reduced by more than a factor of two, and the measurement extends to lower multipoles: $50 < \ell < 2400$. Data from both 95 and 150\,GHz is used, allowing for three cross-spectra: 95 GHz x 95 GHz, 95 GHz x 150 GHz, and 150 GHz x 150 GHz. B-mode power is detected at very high significance; we find $P(BB < 0) = 2.7\times 10^{-30}$, corresponding to a $11.4\,\sigma$ detection of power. An upper limit is set on the tensor-to-scalar ratio, $r < 0.30$ at 95\% confidence. The measured B-mode power is completely consistent with the \textit{Planck} best-fit $\Lambda$CDM model predictions. Scaling the predicted lensing B-mode power in this model by a factor $A_\mathrm{lens}$, the data prefer $A_\mathrm{lens} = 1.01 \pm 0.12$. These data are the best current measurement of B-mode power at $\ell > 300$.

The star formation rates for galaxies in early universe (z >1.0) is observed to be 10 times higher than galaxies in the low redshift (z <0.5) regime. In addition to the SFRs, the conditions of star formation are also found different at high and low redshift regimes and in different environments. To understand what is driving this evolution in star formation rates, and thus the evolution of galaxies, we need to understand the physical conditions such as the electron density of these star forming regions. In this talk, I will present my work on the electron density in a z = 1.6 galaxy cluster.

The origin of magnetic fields in white dwarfs remains an open question with several proposals under investigation. Most intriguing is the idea that magnetic fields in white dwarfs are formed during a stellar merger. One group of white dwarfs, the rare hot, carbon-rich white dwarfs (hot DQs), have an exceptionally high incidence of magnetism and fast rotation as compared to the general white dwarf population. These stars most likely formed from the merger of two white dwarfs, which also created the magnetic field and left the merged white dwarf spinning rapidly. We currently do not know how these stars will evolve as they cool. We have assembled the complete known population of DQ white dwarfs and investigated their properties to identify the cooler and older counterparts of the hot DQ white dwarfs.

Investigating the extreme and sometimes varying nature of active galactic nuclei requires long-term observation of very-high-energy gamma-rays, while studying their flaring episodes (and other transient events) mandates continuous all-sky coverage. Such observations can be obtained with Imaging Air Cherenkov Telescopes (IACT) which detect Cherenkov light emitted by air showers produced when gamma-rays collide with the Earth's atmosphere. While IACTs have the benefit (over other methods) of sensitivity well in to TeV energies, observation time is limited to night hours. The Cherenkov Telescope Ring (CTR) is thus a project to establish a worldwide network of IACTs for long-term continuous observation and 24-hour follow-up availability. As Australia has no pre-existing IACTs, establishing a new site is crucial for the CTR to have full sky coverage. In this contribution the CTR will be introduced, its science cases will be outlined, and weather studies for a potential Australian telescope site will be presented.

A unified understanding of the physical and chemical properties during the early stages of star formation remains an unsolved problem in astronomy today. As molecular clouds are the birthplace of stars, understanding their properties during those stages is crucial to solving this problem. To unravel this matter, we have utilized dendrograms, which are graphical representations (tree diagrams) of the hierarchical structure of the gas found within molecular clouds. This technique allows us to quantify the physical properties of the structures within the cloud and consequently relate that to star formation. Dendrograms have been applied to a large sample of Planck early cold cores (which are objects that trace the early stages of star formation). These cores were observed using the radio telescope at the Purple Mountain Observatory, to produce a catalogue of carbon monoxide molecular line data, of cores located within our Milky Way Galaxy. I provide an overview of the dendrogram method, the data we used, as well as early results from applying this method to the aforementioned dataset.

The formation and evolution of stars drives the evolution of galaxies in the universe at all epochs, from the earliest observable galaxies to our own Milky Way. Whilst the profound importance of star formation and evolution is abundantly clear, the star formation process and the role of turbulence to this day present some of the greatest, unresolved problems facing contemporary astrophysics. With molecular line data from the StarFISH (ATCA Legacy) CS 1—0 survey, and an additional 16 molecular species from the Mopra radio telescope, we will use extended maps of the interstellar medium to investigate the turbulent and star formation properties in a variety of environments, including the G333 and Vela Molecular Ridge C giant molecular clouds. Applying probability distribution function analyses of column density, we will separate the turbulence dominated and gravitationally bound components of the interstellar medium, and determine which molecules trace these regimes. We will also show how a comparison of molecules can be used to distinguish between star forming regions at different stages of development.

ASSET: Astronomy Summer School of East Texas was designed to address the needs of rural schools in east Texas, a region with educational barriers similar to those in rural Australia. This region is populated by poorer schools with few science resources, underperforming students, and “academically unacceptable” school districts, as rated by the Texas Education Association. We created two 10-day workshops to provide a suite of active learning modules to regional secondary teachers. The effectiveness of these workshops was gauged in part through a series of content surveys given to each participant at the beginning and end of the workshop. Similar content surveys were also administered to each teacher’s students as pre/post-content surveys in an effort to determine the extent to which ASSET’s impact on the teachers was transferred to their students. We also interviewed teachers after the subsequent academic year to explore their successes, pitfalls, and confidence in using ASSET materials in the classroom. Overall, students performed best on concepts where teachers exhibited the highest gains in their own learning and, unsurprisingly, in areas where there was greater coverage during the year. A question-by-question analysis, though, suggests that a broad analysis paints an incomplete picture of student learning. Looking beyond these numbers, we present results that support the creation of professional development opportunities designed to increase content knowledge as well as model tools to present such knowledge to their students, which in turn improves student learning and performance, but is dependent on teacher confidence and level of coverage. This project is supported by the NASA Science Mission Directorate Education and Public Outreach for Earth and Space Science (EPOESS), which is part of the Research Opportunities in Space and Earth Sciences (ROSES), Grant Number NNX12AH11G.

The Gravitational-wave Optical Transient Observer (GOTO) is dedicated to searching for optical counterparts associated with gravitational-wave signals, on the strength of its wide field-of-view, of ~20 square degrees. More than 2000 square degrees can be covered in a single night, making it possible for many optical transients to be discovered. Separating real and "bogus" detections can no longer be done manually. Instead, developing an efficient classifier to identify real detections is an essential part of rapid-response astronomy. I developed an algorithm using an Artificial Neural Network (ANN) to separate real and bogus detections based on their morphology. I use a 21-by-21-pixel stamp around each detection to extract features to calculate a real-bogus score. To build a substantial real-bogus training set, instead of using difference images, I used the detections in the science images to create a sample containing 122,772 real detections. The bogus set, containing 97,449 samples, was created by using all detections in the difference images, which likely contain less than 1 percent real-detection contamination. The model was tested on the fake injection recovery test. For those detections that could be picked up by SExtractor at first, the model results in a 94.9 percent True Positive Rate (with a 1 percent False Positive Rate).

Radial velocities for several eclipsing binary systems are being determined with the broadening function method on spectra observed with the ANU 2.3m telescope and Wide Field Spectrograph. The broadening function was developed by Slavek Rucinski to extract velocities from the complex, convolved spectra of rapidly rotating, contact eclipsing binaries. It gives more accurate results for close binary systems than the cross correlation function. It provides information on relative luminosities as well as velocities. The radial velocities of cool components of binaries that appear as single lined can be determined with the broadening function when a template appropriate for cool stars is used. Examples include V775 Cen, a near contact Algol-type binary with chromospherically active components and HM Pup and IZ Tel, both of which are detached Algol-type binaries, with subgiant secondary and pulsating primary components. The luminosities of the secondary components of each of these are only about 5 – 7% of the total of each system. We have observed several contact binary systems, all of which are shown to be triple with the broadening function. TW Crucis is an example of a chromospherically active, contact binary.

Understanding the evolutionary paths and cycles of active galactic nuclei (AGN) is a modern challenge in radio astronomy, with consequences as far reaching as AGN feedback and galactic evolution. A key ingredient at the heart of this problem is a profound lack of understanding regarding what happens during the phase of an AGN where the radio jets switch off. Such sources are expected to display no signs of compact-core activity, while the shocked plasma forming the large-scale lobes is left to fade via Synchrotron energy losses. These rapidly fading low-brightness 'remnants' are extremely difficult to detect, resulting in extremely low remnant fractions even in the most sensitive radio surveys. This presents a major difficulty when attempting to probe the conditions required for AGN activity to terminate and the mechanisms that influence their evolution. This work will exploit a unique, unexplored parameter space in order to develop a statistically rich sample of remnant AGN. The Murchison Wide-field Array (MWA) probes frequencies [72 $-$ 231 MHz] where Synchrotron losses are minimal, making it ideal for detecting remnant AGN. By combining these low-frequency observations with the high-frequency and high-resolution cutting-edge observations of the Australia Square Kilometre Array Pathfinder (ASKAP), we are able to develop key constraints on the energetics, dynamics, past activity and ages of the remnant AGN emission $-$ characteristics which, without the unique combination of data from both the MWA and ASKAP, are difficult to probe. By reconciling these radio-derived characteristics with host galaxy properties we form new understandings regarding the formation and evolution of the remnant AGN phase.

The Milky Way Galaxy formed in part through the accretion of smaller dwarf galaxies. Some of these events remain imprinted on the Galaxy in the form of stellar tidal streams: coherent kinematic and spatial structures of stars. The discovery of these streams has exploded recently thanks to deep photometric surveys (e.g., DES, Pan-STARRS) combined with the precise kinematic information from Gaia. One particular stream, Fimbulthul, has associated with the massive globular cluster $\omega$ Centauri[1, 2], but only with kinematics and metallicities. In this talk, I will use the abundance information from the GALAH survey to confirm this association of the Fimbulthul stellar stream to $\omega$~Centauri using chemical tagging from over 10 elements with a range of dominant nucleosynthetic origins. References [1] Ibata, R. A., Malhan, K., & Martin, N. F. (2019). The Streams of the Gaping Abyss: A Population of Entangled Stellar Streams Surrounding the Inner Galaxy. The Astrophysical Journal, 872(2), 152. https://doi.org/10.3847/1538-4357/ab0080 [1] Ibata, R. A., Bellazzini, M., Malhan, K., Martin, N., & Bianchini, P. (2019). Identification of the long stellar stream of the prototypical massive globular cluster ω Centauri. Nature Astronomy, 1–27. https://doi.org/10.1038/s41550-019-0751-x

The tidal field of Sagittarius A*, the 4×10^6 𝑀⊙ supermassive black hole at the galactic centre is thought to inhibit star formation within ~ 5pc. Recent observations have revealed that the galactic centre is permeated by a hot (4×10^7K) high pressure medium which could compress clouds to densities higher than the Roche density – allowing their self-gravity to overcome tidal disruption. Here I present preliminary results using the tensor virial theorem to model the joint effect of high external pressure and tidal forces. I will present equilibrium cloud solutions, the response to perturbations from this steady state, and the implications of these results for cloud survival and star formation at the very centre of galaxies.

Fast Radio Bursts (FRBs), exotic millisecond duration bursts which are now established as a bona fide astrophysical phenomenon are currently the hottest topic in the field of transient astronomy. The discovery of FRBs has stimulated a range of theoretical investigations to understand their origin and physics as well as observational efforts around the world to search for more such bursts. New instrumentation capable of real-time detection has enabled prompt multi-wavelength follow-ups upon detection. The ongoing SUPERB project at the Parkes radio telescope is discovering FRBs in real time and effecting rapid multi-wavelength follow-ups which are a key to determining FRB progenitors. In this talk, I will present the latest SUPERB FRB discoveries and the results of their radio, optical and X-ray follow-ups. I will also summarise what is happening around the world for the follow-up of FRBs at all wavelengths to motivate further discussion. There is no more exciting time to be involved in the field!

The Large and Small Magellanic Clouds (LMC/SMC), as two of the closest and most massive satellites of the Milky Way, have significant effects on the local Universe; including the distribution of ultra-faint satellites, and the orbits of tidal streams. Ongoing survey efforts with the Dark Energy Camera have revealed a wealth of low-surface-brightness stellar substructures in the periphery of the Clouds; characterising these structures will provide significant insight into the currently poorly-constrained masses and interaction history of the Clouds. In order to elucidate the properties of the structures, we have used 2df+AAOmega at the Anglo Australian Telescope to instigate a large-scale spectroscopic follow-up of stars across the Magellanic periphery. We are able to detect the kinematic signature of the Clouds up to projected distances of 23 degrees from the centre of the LMC. Combining our spectroscopically derived radial velocities with Gaia DR2 astrometry provides the first 3D kinematics for these regions. Our initial set of measurements, along a large substructure to the north of the LMC, reveal radial velocities near the extremity of the substructure are significantly different from those expected from an extrapolation of the LMC rotation curve; this discrepancy may indicate a strong warp in the LMC disk. Our ultimate aim is to use these 3D kinematics to assess dynamical models of the Clouds; this will shed new light on the origin of the substructures, and the evolution of the Magellanic/Milky Way system.

The observation of gravitational waves from merging compact objects has marked the beginnings of gravitational waves astrophysics for ground-based gravitational-wave observatories like LIGO and Virgo. However, these instruments are also searching for other gravitational wave sources. Continuous gravitational waves from rotating neutron stars are persistent, long duration signals at close to monochromatic frequencies. Noise sources can also introduce monochromatic signals into the interferometer data, which proves challenging if searching for a continuous gravitational wave signal near to the affected frequencies. One such noise source in the LIGO observatories originates from the 60Hz American electricity grid. Here we investigate whether signal processing techniques (similar to those used in noise-cancelling headphones) can be used to help continuous gravitational wave searches.

No abstract provided.

The mid-term review (MTR) of the 2016-2025 Decadal Plan for Australian astronomy is due to be published in mid-2020, with community input being requested during the second half of 2019. On behalf of the NCA, I will summarise the MTR process and timeline, and discuss the process for community input. The status of 2016-2025 Decadal Plan priorities will be discussed; potential opportunities that have arisen in the last few years will also be highlighted.

This year, CSIRO's latest national facility radio telescope became fully operational. The Australian SKA Pathfinder offers a new rapid survey capability in the frequency range 700 to 1800 MHz with its 30 square degree field of view. I will describe the capabilities of the telescope, some of the highlights from our early science observations and the remaining steps that will verify the telescope and its associated data processing pipeline are ready to commence multi-year survey projects.

The Australian Square Kilometre Array Pathfinder (ASKAP) uses revolutionary phased array feeds (PAFs) to provide wide-field observations with the sensitivity and resolution required to resolve faint and extended radio emission. I will present the some of the Widefield ASKAP L-band Legacy All-sky Blind surveY (WALLABY) Early Science results being achieve with ASKAP. WALLABY will survey three quarters of the entire sky in neutral hydrogen (HI) to probe the properties of galaxies and their environments. With only a fraction of the array – during the commissioning and Early Science phases of ASKAP – we are already detecting newly resolved HI features, such as tidal streams, intragroup gas and previously unknown HI galaxies. Using ASKAPsoft, the custom-built processing pipeline, we are now producing science-ready image cubes and source catalogues. Our most recent results verify that ASKAP is poised for full operations.

This talk introduces the first large-area survey completed with the full 36-dish Australian SKA Pathfinder (ASKAP) telescope, the Rapid ASKAP Continuum Survey (RACS), and presents some of the first science results. RACS has two main aims: to provide the first iteration of the Global Sky Model that will be needed to calibrate future deep ASKAP surveys, and to provide the astronomical community with a powerful new radio imaging survey of the southern sky. RACS has covered the whole sky visible from the ASKAP site in Western Australia (dec -90 to +40), initially at 744-1023 MHz. The RACS images are significantly deeper than the existing NVSS and SUMSS radio surveys, as well as providing a factor of four improvement in spatial resolution and full polarization information - opening up an exciting new view of the southern radio sky. All RACS survey products will soon be public. They include radio images (with ~12 arcsec resolution) published on CASDA, and catalogues of about 2 million source components with spectral index and polarization information.

The completion of the Australian Square Kilometre Array Pathfinder (ASKAP) now provides the ability to study the transient radio sky to an unprecedented level. The ASKAP survey for Variables and Slow Transients (VAST) aims to fully explore the transient and variable parameter space, from local to cosmological transient phenomena on time scales from seconds to decades. The Rapid ASKAP Continuum Survey (RACS) is the first full southern sky survey being performed by ASKAP covering 27,000 deg$^2$. The survey is designed to provide a base sky model for future observations and reaches a sensitivity of 0.2 mJy/beam using 15 minute integrations. In this talk I will discuss the ongoing VAST analysis where past surveys such as the Sydney University Molongo Sky Survey (SUMSS) and the NRAO VLA Sky Survey (NVSS) are compared with RACS to search for transient and variable sources, to a peak brightness limit of 2 mJy. The search has a timescale of two decades, where AGN activity is expected to be the dominant form of variability, however, there is the prospect of detecting more 'decades-long' transients such as that found by Law et al., 2018 – a candidate orphan afterglow of an off-axis gamma-ray burst. I will also detail the upcoming VAST survey plans for the ASKAP pilot survey period and beyond, including summarising current predictions of what will be detected.

Although discovery technologies are now populating exoplanet catalogs into the thousands, contemporary astronomy is poorly equipped to find the most compelling exoplanetary real-estate: earth-analog systems within the immediate solar neighbourhood. The TOLIMAN space telescope is a low-cost, agile mission concept dedicated to astrometric detection of exoplanets within 10PC, and in particularly targeting the Alpha Cen system. It accomplishes this by deploying an innovative optical and signal encoding architecture that targets the most promising technique for this critical stellar sample: high precision astrometric monitoring. Two pathfinder missions, the first a cubesat slated for launch this year, and the second a 10cm space telescope planned to fly in 2021, are now both fully funded. We will present an overview of the family of missions and the novel technologies underlying the signal detection strategy.

Young jets from active galactic nuclei can inhibit star formation in their host galaxies by injecting heat and turbulence into the interstellar medium (ISM). Near-infrared adaptive optics-assisted integral field spectroscopy is a valuable tool for probing the ISM conditions in the hosts of these sources, enabling us to search for jet-driven feedback on sub-kpc scales. I will present our recent studies of jet-ISM interactions in the nearby compact radio galaxies 4C 31.04 and UGC 05771, which we observed using Gemini/NIFS and Keck/OSIRIS respectively. We detected shock-heated molecular hydrogen and [Fe II] emission in both sources. We also find shocked gas out to kpc scales in UGC 05771 using optical integral field spectroscopy from the CALIFA survey. In both sources, the extent of shocked gas is up to ~100x larger than the extent of the radio source in existing interferometric radio observations, implying that such observations fail to detect kpc-scale jet plasma. This is consistent with our hydrodynamical simulations, which show that the main jet stream may become temporarily halted behind a dense clump whilst secondary plasma streams can percolate through the ISM, forming an expanding bubble. Using IRAM CO observations, we find that UGC 05771 sits below the Kennicutt-Schmidtt relation, although we are unable to conclude whether the jets are inhibiting star formation due to shock contamination in our SFR estimate. Our findings demonstrate the important role that young jets may have in regulating star formation in the host galaxies of compact radio sources, which has implications for galaxy evolution.

The second data release of the SkyMapper Southern Survey has been available to Australian astronomers and their collaborators since March 2019. It improves over DR1 by adding the first batch of deep Main Survey images, by adding data at more epochs and with improved homogeneity of calibration. In this talk I will highlight several science projects pursued by us and enabled by this release, in order to showcase the survey's capacity and entice future users. The science highlights range from luminous QSOs and rare types of QSOs over colour maps of nearby galaxies to black-body stars and blue large-amplitude pulsators. I will close with an outlook for future releases and synergy between SkyMapper and LSST.

The SAMI Galaxy Survey has now completed its observations of over 3000 galaxies. The sample spans a diverse range of environments from the field to rich galaxy clusters. It provides a powerful opportunity to better understand the physical processes that influence galaxy transformations. In this talk I will focus on what SAMI can tell us concerning the transitions driven by environment. Using the spatial distribution of star formation in SAMI galaxies we show that quenching happens from outside to in, in both clusters and groups. However, the timescale for this quenching appears different between clusters and groups, and I will present stellar population measurements to demonstrate this. By combining SAMI data with self-consistent dynamical models I will also discuss the role of environment in morphological transformations, in particular focusing on the evolution of spirals into S0s. We find that while some of the dynamical and structural change in this transformation is caused by the fading a quenched disk, this is not sufficient. Further dynamical processing is required to make the S0s we see in groups today.

Cosmological measurements are becoming sensitive enough to provide the first-ever measurement of the neutrino masses, and to search for completely new particles suggested by recent experiments. I will discuss the effects of these light, fast particles on the formation of large-scale cosmic structure, as well as my recent constraints on them. Then I will describe ongoing work to tackle one of the most difficult problems in theoretical cosmology, the prediction of the non-linear clustering of massive neutrinos, which will be essential for making full use of next-generation cosmic surveys as probes of fundamental physics.

Radio observations of GW170817, the first binary neutron star merger detected by LIGO, were critical in distinguishing between theoretical models for the explosion. Our long term monitoring for a year after the event allowed detailed modelling of the non-thermal emission and subsequent VLBI observations ruled out isotropic ejecta and showed the emission was likely jet-dominated. In this talk I will review what we have learned so far from GW170817 and outline our plans for radio follow-up of gravitational wave events in LIGO O3 and beyond. I will also discuss unbiased radio surveys for short and long gamma-ray burst afterglows which have the potential to discover binary neutron star and neutron star-black hole mergers where the search for prompt optical emission is inhibited by the geometry of the event, the environment of the event, or even terrestrial weather at the time of observations. I will focus on the capability of Australian radio telescopes to contribute to this exciting area of research.

The recently commissioned MINERVA-Australis telescope array is a facility dedicated to the follow-up, confirmation, characterization, and mass measurement of planets discovered by the Transiting Exoplanet Survey Satellite (TESS) orbiting bright stars (V<10). The facility is located at the University of Southern Queensland’s Mount Kent Observatory in Australia. Its flexible design enables multiple 0.7m robotic telescopes to be used both in combination, and independently, for high-resolution spectroscopy and precision photometry of TESS transiting planet candidates. MINERVA-Australis is already delivering a radial velocity precision of 3m/s and continued improvements to the spectrograph’s thermal stability are expected to result in a precision of 1m/s in the near future. It is expected that TESS will discover a large number of planet candidates orbiting bright stars in the coming years, and dedicated facilities such Minerva-Australis are urgently needed to confirm the candidates and characterize them. The predecessor to the TESS mission, Kepler, discovered thousands of exoplanets, the majority of which were between the size of Earth and Neptune (“super-Earth” or “mini-Neptunes”). Unfortunately, the great majority of stars targeted by Kepler were too faint for detailed follow-up work to be performed by all but the world’s largest telescopes. In this sense, TESS is a game changer. It is expected to discover a plethora of Neptune and super-Earth candidates orbiting bright stars that are suitable for high-precision radial velocity follow-up on dedicated facilities such as with MINERVA-Australis. I will discuss the current efforts being made by the MINERVA-Australis consortium to follow-up the planet candidates discovered by TESS to confirm their planetary nature, and to measure their masses and orbital properties. The mass measurements we obtain, when combined with the planetary radii given by the TESS transit observations, will allow us to determine the bulk compositions of those objects and to distinguish them as either rocky, watery, or gaseous worlds. In addition to confirming and measuring the masses of TESS planet candidates, I will also discuss our efforts to probe the processes involved in planet formation and migration. Using MINERVA-Australis, we are measuring the sky-projected spin-orbit angles (i.e., the angle, λ, between the spin angular momentum vector of a host star and the orbital angular momentum vector of its planet) of exoplanets by observing the Rossiter-McLaughlin effect. Of particular importance are spin-orbit measurements of the least explored parameter space such as sub-Jovian planets, warm Jupiters and long-period planets, and multi-planet systems. These measurements are critical in determining the dominant mechanisms responsible for planet migration, whether it is disk-driven migration, or dynamical-migration mechanisms (e.g., planet-planet scattering, Lidov-Kozai cycling with tidal friction, and secular chaos).

In 2015, Advanced LIGO made the first detection of gravitational waves. We now detect gravitational waves on a nearly weekly basis. The signals we observe come from coalescing compact binaries, which can be formed through numerous scenarios. Measurements of orbital eccentricity encoded in the gravitational waveform can be used to distinguish these different scenarios. When two stars co-evolve in the field, they are expected to have negligible eccentricity at detection, whereas dynamically formed binaries can retain measurable eccentricity. In this talk, I explain how different formation channels lead to different distributions of eccentricity. I present the results of a search for eccentricity using ten events from the first gravitational-wave transient catalogue. Finally, I show how future detectors will enable us to trace the evolution of globular clusters by tracking the relationship between redshift and eccentric merger rate.

Type Ia supernovae (SN Ia) have been used as cosmological distance indicators for the past two decades. The quality of SN Ia observations has increased dramatically over time, and so too must our methods for fitting their distances. In particular, we must work to minimise systematic errors, as further understanding of dark energy is now limited by systematic rather than statistical errors. In this talk, I will introduce the current state of supernova light-curve and distance fitting. I will show the issues and improvements to fitting methods that I’ve been researching in the context of the Dark Energy Survey, and show how the improvements propagate through to improvements in the measurements of dark energy.

The cosmological constant problem arises because the magnitude of vacuum energy density predicted by quantum field theory is about 120 orders of magnitude larger than the value implied by cosmological observations of accelerating cosmic expansion. Recently, a stochastic toy model of quantum vacuum fluctuations was developed which suggests a new resonance-based mechanism for the slowly accelerating expansion of the universe, potentially resolving this tension [Wang et al, Phys. Rev. D 95, 103504, 2017]. In recent work [Cree et al, Phys. Rev. D 98, 063506, 2018], we thoroughly investigated the dynamics of this model, extending it in new ways. I’ll present our results showing the effects of varying both the number of particle fields and the choice of ultraviolet cutoff for vacuum fluctuation frequencies. I'll also introduce a new analytic method using the Mathieu equation (a prototypical example of parametric resonance) that closely matches numerical results. We find that this toy model provides evidence that resonance of fluctuations can explain the slowly accelerating expansion of the universe.

We are conducting a systematic survey for $z<0.04$ active galactic nuclei (AGNs) that have changed spectral class over the past two decades. We use Skymapper, PanSTARRS and the Veron-Cetty \& Veron catalogue to search most of the sky for these ``changing look'' AGNs using a variety of selection methods. We use $riz$ aperture photometry to identify changing look AGNs, using $r-i$ color as a proxy for ${\rm H\alpha}$ equivalent width. We measure change in photometry over time by calculating the difference between PanSTARRS and Skymapper photometry and SDSS photometry, where a change in photometry may indicate a change in spectral type. NEOWISE multi-epoch photometry is also used to select changing look AGN candidates that change photometry over time. Our recent observations with the 2.3m Siding Spring Telescope WiFeS has discovered two new changing look AGNs. We identify a new changing look AGN, NGC 1346, using archival data alone, which changed spectral type from type 1 to type 2 between 2001 and 2004. Using photometry we attribute the change in spectral type of NGC 1346 to accretion rather than a simple lumpy torus.

Powerful radio galaxies — by displaying simultaneously active supermassive black hole (SMBH) and vigorous on-going star formation — are unique laboratories to study the impact of the SMBH feedback on its host galaxy. Moreover, the orientation in the plane of the sky allows the dusty torus to act as a natural coronograph, shielding us from the intense radiation from the accretion disc, thus, enabling the possibility to study the host galaxy. Using the efficient steep-spectrum selection technique from low-frequency radio surveys, we were able to build large samples of galaxies confirmed out to z=5.2 more than two decades ago. This provided us with the unique chance to study the physical properties of the progenitors of our local massive elliptical galaxies during the peak of the activity of the Universe (z~2-3). However, progress in finding more distant sources has been slow due to the lack of deep all-sky surveys at low frequencies. We designed a new technique making use of the new generation of low-frequency radio surveys in order to push our samples beyond the twenty-years old limit of z=5.2. I will present the results of our pilot programme on the VLT, ALMA and ATCA for a selection of sources from the GLEAM (an all-sky survey at 70-230MHz executed by the MWA). This technique has already shown its efficiency to detect a z=5.55 source with a potential candidate at even higher redshift.

Active Galactic Nuclei (AGN) play an important role in the evolution of galaxy clusters and groups. One way they influence their host is through feedback from radio jets, which do work on their host hot atmospheres through supersonic outflows, shocks, and gas uplifting. Modelling the evolution of these radio jets is key to understanding their effects on the surrounding environment. Analytic models are able to predict large-scale radio lobe properties, or smaller-scale jet properties, but they can't capture all physical processes relevant to jet-environment interaction; this is where numerical models of radio jets are needed. Observational studies using data from the Radio Galaxy Zoo citizen science project (Rodman et al. 2019) have shown that there is often an observed environment asymmetry between the lobes of a radio source; this is something that cannot be studied properly with analytic models, but is expected to have a large effect on radio source evolution. We have studied the effect of asymmetric environments on radio source evolution, through state-of-the-art numerical three-dimensional simulations of a pair of relativistic jets. We find that environment asymmetry affects jet collimation distance, large-scale lobe morphology, and the observable radio source properties. Because the two bipolar jets are intrinsically identical, the observed asymmetry provides a probe of the jet's hot gas environment, a quantity which is notoriously difficult to measure. These models provide tools for interpreting environment-sensitive surveys with next-generation radio and optical/IR facilities. We present methods for understanding observations of asymmetric radio sources, and detail how they can provide information about the underlying structure of galaxy groups and clusters.

To properly understand the detailed process of galaxy formation and evolution there is an urgent need to identify and quantify the role of AGN feedback, not only through detailed studies in the local Universe, but also at high redshifts, where most of the accretion occurred. While the bright radio sky is dominated by the emission driven by radio-loud (RL) AGNs, at fainter flux densities (<0.5-1 mJy) the contribution from star-forming galaxies (SFGs) and radio-quiet (RQ) AGNs (i.e. AGN which do not display large scale jets and lobes) becomes increasingly important. The detection of large numbers of RQ AGNs, traditionally studied at optical/IR or X-ray wavelengths, opens new exciting perspectives for deep continuum-radio surveys, providing a unique and powerful dust/gas-obscuration-free tool to get a global census of both star formation and AGN activity up to high redshifts; hence tracing the apparently simultaneous development of the stellar populations and the black hole growth in the first massive galaxies. In this talk I will give an overview of our current understanding of radio-selected RQ AGN and of the origin of their radio emission.

Orientation has long been envisioned to play a role in the basic unification scheme of quasars. Though the true structure of quasars remains unclear, it is often portrayed to be axially symmetric, suggesting that there is some dependence with the angle of viewing. A number of orientation indicators have been suggested in the optical, yet none has provided a convincing easy-to-measure test. We present a UV-optical orientation tracer using the correlation between the velocity shifts and the line width ratio of CIV and MgII lines. Comparison tests with other orientation indicators and simulations are shown to be consistent with our idea.

While hunting for exoplanets, the Transiting Exoplanet Survey Satellite (TESS) serendipitously provides us with 30 minute cadence photometry of large patches of the local universe, allowing us to analyse extragalactic transients. By utilising ground based telescopes to discover supernovae (SNe) that occur within the TESS fields, we have triggered early spectroscopic time series of young SNe, allowing us to see the spectral signatures of shocks unfold before peak brightness. The high cadence photometry of TESS enables us to produce exquisite light curves of these shocks in real time; a feat which has seldom been successful in the past. In this talk, I will present the work done to date in finding these shock signatures and subtle features in exotic transients.

The intrinsic variability of stars can hinder the search of terrestrial-mass planets and the precise characterisation of these planets. Such stellar variability can induce spurious radial velocities, generically referred to as "jitter", mimicking the presence of exoplanets. The key to this line of research is understanding the radial velocity impact of line profile variability in a measurable way. 

I have developed a Fourier phase spectrum analysis (FIESTA) technique to study a spectral line profile in the Fourier domain. A pure shift of a line profile is equivalent to shifting all the decomposed Fourier basis functions of all Fourier frequencies by the same amount, while a line deformation is effectively the result of applying different shifts of the Fourier basis functions at different Fourier frequencies. As a result, it translates an abstract line deformation into the measurable shifts. Besides, FIESTA enables differentiating an intrinsic line shift from an intrinsic line deformation, which had not been robustly attainable by previous methods (e.g. employing stellar activity indicators). FIESTA may also be universally used to quantitatively identify a signal shift versus a signal deformation.

Observations of protoplanetary disks at multiple wavelengths have revealed spectacular disk morphologies, including spiral arms, circular and eccentric dust cavities, and azimuthally asymmetric dust horseshoes. All these can be caused by the interaction of companions, of planetary or stellar mass, embedded within the disk. Using numerical simulations, I have been exploring how changing the properties of a companion in a disk changes the disk morphology. By including a stellar companion, I have found it is possible to create dust horseshoes with high contrast ratio, as observed in IRS48, without vortexes. Although no high mass companion has yet been confirmed in this disc, I will show how a companion with mass on the order of 0.4 Msun can explain the dust trap, and the asymmetric CO kinematics in this disc. My results indicate that asymmetrical dust horsehoes are the result of dynamical interactions between the host star, the companion, and the disc. These results bring in to question the common interpretation that dust traps in protoplanetary discs are caused by large scale vortices, which has consequences for some planet formation hypotheses. This interpretation makes clear predictions about the CO kinematics of the IRS48 which may be detectable with ALMA.

In the coming years, we will begin to discover the first truly Earth-like planets orbiting other stars, and the race will be on to search for any evidence of life upon them. But how will we choose where to look? In this presentation, I will examine one piece of that puzzle, showing how we might be able to use dynamical methods to filter the list of potentially habitable worlds for those that should be considered the most promising targets for that search. I will present the results of detailed n-body simulations of alternative versions of the Solar system. By examining how the long-term evolution of the Earth's orbit changes as a function of the initial orbits of the other planets, I will demonstrate how we can assess the amplitude and frequency of the Milankovitch cycles that will control the scale and pace of periodic climate variation on the alien worlds we discover.

I will give an overview of searches for different dark matter candidates within the global-fitting framework GAMBIT. I will touch on supersymmetric, Higgs portal and axion theories, and draw together constraints from direct and indirect detection, cosmology, solar physics, laboratory experiments and high-energy colliders.

As the number of observed rotational glitches in pulsars grows, thanks to UTMOST and other observing programs, it is useful to not only disaggregate the data into individual pulsars, but to also consider the time-ordered nature of these events. The shape of waiting time and glitch size distributions, cross-correlations, and autocorrelations are all avenues that can test the applicability of a generic, statistical, stress-release model for glitches. The model produces precise, quantitative, falsifiable predictions regarding long-term glitch statistics. Reconciling observations with the model leads to implications as to which physical mechanism may be causing glitches in pulsars.

2019 is appearing to be a turning point for Astronomy Education worldwide. The International Astronomical Union (IAU) has called for bids to host the fourth and final official IAU office, the Office of Astronomy Education. This is expected to be finalised by the end of the year. The IAU, involving a group of international collaborators led by Leiden University, has also recently completed a Proposed Definition of Astronomy Literacy, now available online for comment and critique. A similarly large and similarly international group led by the speaker has also recently completed a complimentary review of the K-12 curricula around the OECD countries (including South Africa and China). The speaker will provide an overview of the recent international developments in astronomy education focussing on the projects mentioned above, but also summarising some of the current smaller, but equally important, Astronomy Education-related activities spread around the globe. Australia, in particular, has played a central and continuing role in many aspects of international astronomy education with three Division C (Education) executive positions held by ASA members at the IAU and multiple international projects involving Australian collaborators in leadership positions. The talk will conclude with potential directions forward in Australian and International Astronomy Education. (Only available on the 9th)

We report the discovery of a new Small Magellanic Cloud pulsar wind nebula (PWN) at the edge of the supernova remnant (SNR) DEM S5. The pulsar powered object has a cometary morphology similar to the Galactic PWN analogues PSR B1951+32 and ‘the mouse’. It is travelling supersonically through the interstellar medium. We estimate the pulsar kick velocity to be in the range of 700–2000 km s−1 for an age between 28 and 10 kyr. The radio spectral index for this SNR–PWN–pulsar system is flat (–0.29 ± 0.01) consistent with other similar objects. We infer that the putative pulsar has a radio spectral index of –1.8, which is typical for Galactic pulsars. We searched for dispersion measures up to 1000 cm−3 pc but found no convincing candidates with an S/N greater than 8. We produce a polarization map for this PWN at 5500 MHz and find a mean fractional polarization of P ∼ 23 per cent. The X-ray power-law spectrum (Γ ∼ 2) is indicative of non-thermal synchrotron emission as is expected from PWN–pulsar system. Finally, we detect DEM S5 in infrared (IR) bands. Our IR photometric measurements strongly indicate the presence of shocked gas that is expected for SNRs. However, it is unusual to detect such IR emission in an SNR with a supersonic bow shock PWN. We also find a low-velocity H i cloud of ∼107 km s−1 that is possibly interacting with DEM S5. SNR DEM S5 is the first confirmed detection of a pulsar-powered bow shock nebula found outside the Galaxy.

The cosmological origin of gamma-ray bursts necessitates gravitational lensing. Yet in the 50 years since their discovery not a single convincing candidate has been found. We present what we believe to be the first gravitationally lensed gamma-ray burst pair. The lens candidate is of order 100,000 solar masses, and we will discuss the likelihood of this object being a stellar cluster or compact object.

We present studies of magnetar XTE J1810-197 during its recent radio revival using the new Ultra-Wideband Low receiver system of the Parkes radio telescope. Ultra-wideband (704-4032 MHz) polarization pulse profiles, single pulses, and flux density measurements are presented. The anomalous X-ray pulsar XTE J1810-197 was the first magnetar found to emit pulsed radio emission. After spending almost a decade in a quiescent, radio-silent state, the magnetar was reported to have undergone a radio outburst in 2018 December. We observed dramatic changes in polarization and rapid variations of the position angle of linear polarization across the main pulse and in time. The pulse profile exhibits similar structures throughout our three observations (over a week timescale), displaying a small amount of profile evolution in terms of polarization and pulse width across the wideband. We measured a flat radio spectrum across the band with a positive spectral index, in addition to small levels of flux and spectral index variability across our observing span. The observed wideband polarization properties are significantly different compared to those taken after the 2003 outburst, and therefore provide new information about the origin of radio emission.

Measuring the cosmic star formation history (SFH) is essential to our understanding of the build-up of stellar mass in our Universe. SED fitting techniques, which use multi wavelength photometry from galaxies in the low-$z$ Universe to infer their SFHs, are becoming increasingly popular to measure the cosmic SFH as an alternative to star formation rate measurements at different epochs of the Universe. Up until now, however, the cosmic SFHs derived from such techniques have not shown good agreement with observations. In this talk, I will present results using a new nonparametric SED fitting code \textsc{ProSpect} to derive star formation histories of $\sim 6000$ low-$z$ galaxies from the GAMA survey to infer the cosmic SFH. I will show that this implementation has provided a marked improvement when compared with the results of other SED fitting techniques. These results highlight the power of ProSpect as an SED fitting technique to produce more realistic SFHs of galaxies.

The chemical evolution of galaxies is governed by the chemical yields from stars, especially from Asymptotic Giant Branch (AGB) stars. This underlines the importance of understanding how AGB stars produce their elements by obtaining accurate stellar nucleosynthetic yields. Although AGB nucleosynthesis has general validity, critical uncertainties (such as the treatment of convective-driven mixing processes and mass loss) exist in current stellar models. Furthermore, AGB nucleosynthesis is highly dependent on initial mass and metallicity. For instance, depending on the initial mass and metallicity at which the hot bottom burning process is activated, the model predictions on third dredge-up efficiency, final C/O ratios, and elemental abundances (such as C, N, O, Na, Mg, Al, Li, F etc.,) significantly vary. Observations from Post-Asymptotic Giant Branch (post-AGB) stars serve as excellent tools to confront predictions from a dedicated suite of stellar models, quantify the strongest discrepancies, and eliminate crucial uncertainties that hamper stellar modelling. Past attempts have been hampered by non-systematic and small samples of post-AGB stars, and poorly determined parameters such as initial mass. By strategically integrating the Gaia survey with detailed chemical abundance studies of post-AGB stars in our Galaxy, and the LMC/SMC, we are building a comprehensive data set of elemental and isotopic abundances of post-AGB stars as a function of initial mass and composition. In this talk, I will present our unique data set and our efforts to eliminate and unify the treatment of uncertainties in theoretical stellar models.

Magnetic fields are everywhere: from our Galaxy, to powerful active galactic nuclei (AGN), to galaxy clusters, and the intergalactic medium (IGM). The overall distribution of magnetic field strengths in the IGM, and their dependence on redshift, is a “must know” feature in uncovering the history of magnetic field evolution. While we cannot measure cosmic magnetic fields directly, they do affect light in ways we can observe. One of the most powerful techniques to investigate magnetic fields is through Faraday rotation, or rotation measures. Rotation measures provide information about the magnetic fields along the line of sight, including contributions from the Galaxy, extragalactic sources, the IGM, and the environment local to the emitting source. This can be useful, however, precise RM measurements are needed (and many of them), along with detailed information about the emitting sources, are needed to disentangle the cosmic magnetic field information from all the rest. There are several different possible methods for using the rotation measures of extragalactic sources to try to detect the IGM. This talk will cover recent works using different methods with currently available data, and show why SKA and SKA pathfinder polarisation surveys can’t come soon enough.

Much has been made of the potential of fast radio bursts (FRBs) to discern the whereabouts of the large reservoir of all baryonic material of the Universe that resides in intergalactic space. The dispersion measures of FRBs are capable of accounting for all the ionized baryons along their lines of sight. This renders them the ideal instrument both to weigh the baryonic content of the Universe and to investigate how galactic feedback processes pollute the intergalactic medium. We use the redshifts of several well-localised CRAFT FRBs to weigh the baryonic content of the Universe. We also directly examine the baryonic halo of a massive intervening system intersected by an FRB sightline to derive its density, magnetic field and turbulence properties. In addition, we describe the environments of the FRBs themselves.

Radio pulsars provide one of the great natural physical laboratories. The pulsar timing technique enables tests of strong-field gravity, constraints on nuclear equations of state and the strong nuclear force; probes the extremes of electromagnetism; and is being used to detect low-frequency gravitational waves. However, pulsars are faint sources, and these experiments have been limited by the sensitivity of existing radio telescopes. There is about to be a paradigm shift in pulsar timing, in the form of the MeerKAT telescope in South Africa, which is a factor-of-eight more sensitive than comparable southern facilities and has commenced regular pulsar timing observations this year. In this presentation, I will outline the capabilities of MeerKAT that make it a game changer for pulsar timing. I will provide an overview of MeerTime, a MeerKAT project that will spend 5,500 hours over the next 5 years monitoring pulsars. This will include an overview of the major science goals of the project, namely the detecting of low-frequency gravitational waves through pulsar timing array observations, testing of general relativity by tracing the shapes of binary-pulsar orbits, and establishing the pulsar emission mechanism through regular observation of every pulsar in the southern sky. I will highlight some of early results from the telescope. These include the highest precision observations of a pulsar ever obtained and new views on faint pulsars in the Magellanic Clouds. I will conclude by discussing the outlooks for pulsar timing with MeerKAT and the Square Kilometre Array (SKA), and how MeerTime is being used to prototype SKA regional data centre activities.

Ever since the exoplanet era began, we astronomers have come across some truly bizarre and diverse exoplanetary systems. The physical and chemical processes that produce these systems, along with planetary atmospheres, surfaces and bulk compositions are incredibly complex. Yet, there seems to be some tantalizing evidence suggesting that stellar abundances are playing an integral role in determining certain aspects of the chemical, geological and physical constraints of exoplanets and exoplanetary systems. For example, C/O ratios of stellar hosts and planetary atmospheres could potentially aid us in understanding the formation mechanisms of hot-Jupiters whilst Mg/Si and Fe/Si ratios can help determine the geological and chemical structure of larger terrestrial and smaller gassier worlds. Obtaining high precision measurements of stellar chemical abundances, in addition to stellar physical properties, is crucial for this understanding. However, relative uncertainties in stellar properties, some as high as 100% (e.g TESS Candidate Target List), hinders astronomers and planetary scientists alike in accurately shaping an exoplanetary system’s structure. Until now. By cross-matching stars from Australia's GALactic Archaeology with HERMES (GALAH) with stars being observed by NASA's Transiting Exoplanet Survey Satellite, we have derived the stellar mass and radii of 40,000 potential planet-hosting stars to 3-5% precision using high resolution spectra. The self-consistent stellar parameters (Teff, Logg, Vsini, Radius, Mass, Age etc.) combined with the chemical abundances for 30 elements ([X/Fe]) including iron, silicon, magnesium, carbon, oxygen, aluminium, nickel to name a few, will assist follow-up teams to determine the chemical and geological makeup of newly found exoplanets like never before. This newly derived catalogue already contains several planet-hosting stars, which I will summarise general patterns with other known planet hosts from the K2-HERMES survey. Lastly, I describe how the Southern Hemisphere's only dedicated observatory to TESS follow-up, Minerva-Australis, is aiding other astronomers in determining stellar abundances from spectra used to discover and confirm TESS candidates.

During the first two observing runs of advanced LIGO/Virgo we detected eleven sources of gravitational waves. The sources identified in the first gravitational-wave transient catalog have enabled many novel astrophysical inferences from constraints on the nuclear equation of state, to independent measurement of the Hubble constant, to inferences about the mass and spin distribution of merging binary black holes. In this talk, I will describe the state of astrophysical inference with gravitational waves and the potential discoveries which will be possible in the coming years.

Galaxy mergers play an important role in how galaxies evolve over time, however extragalactic astronomers do not yet totally understand the process by which those mergers happen. The brightest galaxies of groups and clusters are extremely luminous galaxies, usually located in the centres of those systems – central galaxies. Simulations predict that these central galaxies have undergone more mergers than other similarly luminous galaxies, making them an excellent test of the merger process. The recent merger history of galaxies can be read through their stellar population gradients. Central galaxies with active merger histories are predicted to have shallower metallicity gradients than satellite galaxies of a similar mass. We are examining the stellar population gradients (age, metallicity and alpha-element abundance ratios) of central galaxies in the SAMI galaxy survey to determine whether they are offset from similarly massive satellite galaxies in order to reach a better understanding of the role of mergers in galaxy formation and evolution.

Many short Gamma-Ray Bursts (sGRBs) have an extended afterglow in the X-ray spectrum. These afterglows last for thousands of seconds with near constant luminosity. This suggests ongoing energy injection into the system after the initial burst. One natural candidate for a central engine is a long-lived millisecond magnetar. A magnetar can naturally produce a plateau at X-ray frequencies in a model inspired by plerion-like young supernova remnants. An analytic, plerion-like model reproduces key observational features seen in sGRB plateaux e.g. a correlation between the plateau duration and brightness. This opens the door to exciting possibilities in multimessenger astronomy and neutron star physics.

There is a divide in physics, a chasm between the physics of the small (quantum mechanics and the Standard Model of Matter) and the heavy (general relativity). Unifying these theories, and explaining dark matter and dark energy requires new fundamental physics theories (1,2). Many of these new theories predict the variation of one or more fundamental constants (3) such as the proton-to-electron mass ratio, over time. Being able to more accurately measure the variation of the proton-to-electron mass ratio could revolutionise physics (4) by allowing us to filter through the currently competing fundamental physics theories. The most sensitive tests of temporal or spatial variation in the proton-to-electron mass ratio rely on the fact that changing this ratio changes the frequency of spectral transitions, a measurable quantity. Therefore, by comparing the frequency of molecular spectral transitions from distant astrophysical sources to their frequency today, scientists can perform high accuracy tests for variations in the proton-to-electron mass ratio, which have (with some assumptions) currently constrained the variation to less than 1 part in 10^(-17) /yr. To improve on existing measurements, we are aiming to systematically look at spectral transitions from a large number of molecules found in space and identify those transitions that are most likely to allow a very high sensitivity measurement. We will be utilising existing and new computational models of the rovibrational or rovibronic spectroscopy of these molecules, then varying the proton mass to investigate the effect on the molecule’s transition frequency. The size of each spectral shift is quantified by sensitivity coefficients K (4). Most previous theoretical studies have focused on finding large K while not simultaneously explicitly considering a range of other criteria that affect the sensitivity of the astrophysical measurement – for example, the intensity of the spectral line, its frequency, available telescopes and their resolution, and the molecule’s astrophysical abundance. In a joint theoretical-astronomical partnership, we are developing a thorough set of criteria by which a particular molecule and its transitions can be assessed, then apply these criteria on a wide range of molecules. Our ultimate goal is to determine the optimal molecules and spectral transitions to test whether the proton-to-electron mass ratio has changed over cosmological time. References: (1) Stadnik, Y. V.; Flambaum, V. V. Physical Review Letters Nov. 2015, 115, 201301. (2) Uzan, J. Living Reviews in Relativity Dec. 2011, 14, 2. (3) Kozlov, M. G.; Levshakov, S. A. Annalen der Physik July 2013, 525, 452 471. (4) Jansen, P.; Bethlem, H. L.; Ubachs, W. Journal of Chemical Physics 2014, 010901, DOI:10.1063/1.4853735.

Authors: L.A.Tilahun, D.Fisher, K.Glazebrook Centre of Astrophysics and Supercomputing, Melbourne, VIC We study the stellar population properties of massive star-forming clumps in gas-rich, turbulent disk galaxies. Massive star-forming clumps at z=1-3 are thought to play critical roles on the build-up of either bulges or thick disks. Therefore, in order to build an accurate galaxy evolution models, we need to understand the detail properties of clumps. However, due to observational constraints such as, resolution and wavelength coverage the fate of clumps remains poorly understood. In this poster, I will show progress towards on the measurements of mass and age of clumps, and whether clumps are long-live or short-lived. We use a sample of local galaxies called Dynamics of Newly-Assembled Massive Object (DYNAMO), which are very similar to z~2 main sequence galaxies. Previous work shows that DYNAMO galaxies are rare local galaxies that have similar kinematics, gas fraction and morphology to those of high z main sequence galaxies. I will show results on HST observations of DYNAMO sample from wavelengths from 225 nm to 1.2 $\mu$m. In comparison to studies at $z>1$ our observations uniquely can make resolved observations in rest-frame near-IR, which better constraint mass-to-light ratio and to distinguish the dusty young stellar population from intermediate age and old population. Integral spectra energy distribution (SEDs) are our primary source of information about the stellar populations of unresolved galaxies. I will show results on physical properties of clumps measured through fitting SED with well-tested techniques of stellar population synthetic models and discuss the fate of clumps.

Magnetically-driven disc winds have significant effects on the evolution of protoplanetary discs, via the removal of angular momentum and mass from the disc. However, existing models typically ignore non-ideal magnetohydrodynamic effects, such as Hall drift, but these are known to operate inside these discs, and affect their structure and evolution, for example suppressing magnetically-driven turbulence and magneto-rotational instability. In my poster, I will present preliminary results of self-similar disc wind models which include non-ideal magnetohydrodynamic effects within the disc.

The observation and study of atoms and molecules play a critical role in understanding many physical processes from gas clouds to galaxies. By using observations from low-frequency radio telescopes we can study the molecules and atoms that are in the deep dark regions of our Galaxy and the far reaches of the Universe. The cold neutral medium and compact HII regions contain atoms up to the size of a virus and cold polar molecules (e.g. CH) that provide opportunities to test our fundamental understanding of physics and chemistry. In this talk I will discuss my research utilising the Australian Square Kilometre Array Pathfinder (ASKAP) and the Murchison Widefield Array (MWA). Utilising the innovative design of these telescopes we can start studying dark molecular clouds in unprecedented detail and in a frequency range that has rarely been explored. I will also discuss how I intend to exploit this technology to find new molecular rich regions within our Galaxy and to use ASKAP's revolutionary design to study the role magnetic fields play in early star formation through polarised molecules.

On April 1st, 2019, the Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO) and the Advanced Virgo observatories started a joint observing run (O3). Given the recently upgraded sensitivities of both observatories, this new observing run will surely bring novel results with it. One such possibility is the discovery of continuous gravitational waves (GW) from sources such as Low Mass X-Ray Binaries (LMXBs) or Accreting X-ray Pulsars (AXPs). To this end, a new method to search for these sources based in the Viterbi Algorithm was developed. This method efficiently tracks the wandering GW emission frequency one expects from both LMXBs and AXPs. The proposed poster will explain the previously-published Viterbi method, along with its planned improvements. The poster will also discuss its uses in searching for Sco-X1 in the O3 run as well as future applications such as finding X-ray pulsations from LMXBs or in searching for transient GWs.

The past decade has seen the first large IFU surveys of our local Universe, with observations from SAMI, MANGA and Atlas3D shedding light on the spatially-resolved properties of galaxies at $z\sim0$. Similarly, at $z>1$, results from the KROSS, KMOS-3D and SINS surveys have revolutionised our understanding of high-redshift star forming galaxies (SFGs). Taken together, we have evidence for a wide disparity between the turbulent, star forming disks of earlier epochs and the quiescent, ordered spirals we see today. When, how and why did these transformations occur? Furthermore, it is well known that the environment a galaxy resides in plays a role in its evolution, with galaxies in dense clusters experiencing physical processes which do not occur in the “field”. The importance of such environmental effects, however, is still heavily debated in the literature. The KMOS-CLASH survey (K-CLASH) aims to study these areas. K-CLASH measures the spatially-resolved properties of ~100 SFGs at $0.2 < z <0.6$ in four massive CLASH clusters. Our sample consists of SFGs residing in the CLASH clusters themselves, as well as field galaxies along the line of sight. I will present a summary of the survey and describe my work measuring differences in the spatial extent of star formation between our cluster and field samples.

We review the orbital parameters and stellar properties of known close double degenerate systems. We also evaluate our prospects for the identification of merger candidates and bona fide pre-SN Ia systems. Finally, we present a detailed analysis of two double-degenerate systems that also show peculiar atmospheric properties that are most likely the result of two consecutive common-envelope phases.

Spatially unresolved observations of the 21cm HI emission line have proven to be a powerful and inexpensive probe of galaxy properties such as their total HI mass, peak rotational velocity, and cosmological redshift. As radio astronomy enters the era of the SKA, precursor surveys such as WALLABY are predicted to increase the number and quality of global HI spectra by an order of magnitude over current datasets. Extracting as much information as possible from these spatially unresolved observations is essential if we are to exploit these next generation surveys to their full potential. In particular, the asymmetry of global HI spectra might trace disturbances in the kinematics and/or distribution of the HI gas. I will present the results of HI asymmetry measurements using the extended GALEX Arecibo SDSS Survey (xGASS), a targeted survey with deep HI observations of a representative sample of local galaxies. This makes xGASS an ideal sample for determining the properties of HI asymmetric galaxies and constraining their driving mechanisms.

Cosmic rays are the most extreme particles in the Universe and are detectable on Earth. The radio emission produced by cosmic rays when they interact with the Earth’s atmosphere is an excellent tracer of their properties. The low radio frequency interference environment of the Murchison Widefield Array (MWA) makes this instrument ideal for detecting and measuring this radio emission and therefore the study of high energy cosmic rays. From the radio information, the characteristics of the particle such as energy, incident direction, and species have to be reconstructed, aided by the use of air shower simulations. However, the pulses produced by these air showers occur on timescales of the order of 15 ns and the standard output time resolution of the MWA is 100 microseconds. In this talk, I present the status of cosmic ray detection at the MWA and, in particular, the development of an algorithm to access higher time resolution. I will describe the computational performance of this algorithm and the efficiency at which it reconstructs this higher time resolution. I will also report on the deployment of a prototype particle detector at the Murchison Radio Observatory and the plans for future experiments with the MWA.

We present the initial results from a broadband analysis of compact polarized radio sources from the QUOCKA survey. The QUOCKA survey, conducted using the Australia Telescope Compact Array (ATCA), is designed to study the structure of AGN jets, lobes and their surroundings through linear and circular polarization. Our selected sources were observed over 1.3-8.4 GHz. By modelling the frequency dependence of individual polarized emission components, we identified multiple polarized emission components in a source, and characterized their properties.

Active M-dwarfs are known to produce bursty radio emission, and multi-wavelength studies have shown that Solar-like magnetic activity occurs in these stars. However, coherent radio bursts from active M-dwarfs have often been difficult to interpret in the Solar activity paradigm. In this talk, I will discuss Australian Square Array Pathfinder (ASKAP) observations of UV Ceti at a central frequency of 888 MHz. These are the longest continuous radio-frequency observations of this star to date. We detect several periodic, coherent bursts occurring over a timescale consistent with the rotational period of UV Ceti. The properties of the bursts show that they originate from the electron cyclotron maser instability, in a cavity approximately 7 orders of magnitude less dense than the mean coronal density at the estimated source altitude. These results represent the first unambiguous confirmation of auroral magnetospheric activity in an active dMe star. This suggests that these stars mark the beginning of the transition from Solar-like to auroral magnetospheric behaviour. Our results demonstrate the capabilities of ASKAP for detecting polarized, coherent bursts from active stars and other systems.

Last year, I introduced the PRISM pipeline, an alternative to MCMC for rapid analysis of models. This year, I would like to present the improvements that have been made to PRISM and the first scientific results of using PRISM together with Meraxes, one of the core SAMs within ASTRO 3D's Genesis project.

The nature of dark matter is one of the largest mysteries within the cosmological standard model. New, hydrodynamic simulations allow the distribution of dark matter and its interaction with galaxy formation processes to be simulated to greater resolutions than ever before, helping to constrain its properties. Using high-resolution, hydrodynamic, cosmological simulations of Milky Way-type galaxies from the Latte suite, it can be determined if small scale, coherent, dark matter structures persist in galaxy realizations. These provide insight into the potential distribution in real galaxies and their fly-through rates in detectors on Earth. By sampling dark matter populations within the solar neighbourhood and implementing a series of frame transformations, the frame-dependent velocity distribution functions can be used to constrain the parameter space for these Earth-based direct detection experiments.

Galaxy environment is known to have a strong influence on how galaxies evolve. Studies of multiphase circumgalactic medium (CGM) of group environments have revealed significant differences in absorption line equivalent widths and velocity spreads compared to isolated galaxies. A simplistic understanding of the CGM suggests that the metallicity could increase in group environments due to stronger outflows driven by enhances star formation. However, the CGM metallicity of group environments has not yet been explored. To address this, we use the “Multiphase Galaxy Halos” survey, which has a combination of HST UV quasar spectra and imaging as well as Keck and VLT high-resolution quasar spectra, to calculate the CGM metallicity of 13 absorbers in group environments. We suggest that the mass ratio of the galaxies in the groups may affect the CGM metallicity, however, we do not detect any significant difference between group and isolated environments. Environmental effects may only play an important role in determining the CGM metallicity when galaxies are strongly interacting or merging.

The physical conditions in the narrow-line regions (NLRs) of active galactic nuclei (AGN) may be constrained by comparing spectroscopic observations with photoionisation models. The key parameters are the gas-phase abundances, the ionisation parameter, the gas pressure, and the shape of the ionising spectrum. A model of the ionising continuum radiation in Seyfert AGN is discussed. The full data release of the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7) is presented. Three-dimensional data cubes, two-dimensional emission-line fits, and other products have been provided to the astronomical community, along with a large number of maps of gas kinematics across the S7 sample. A Bayesian code is presented that compares photoionisation model grids with observed emission line fluxes. This code NebulaBayes is agnostic to model parameters, dimensionality, and the chosen emission lines. Grids of MAPPINGS photoionisation models have been calculated and used with NebulaBayes to infer physical parameters in two dimensions across four 'pure Seyfert' galaxies selected from the S7 sample. The results are the first robust two-dimensional measurements of gas-phase metallicity in Seyfert NLRs, and show steep metallicity gradients into extraplanar ionisation cones in the case of edge-on galaxy NGC 2992, and an inverse metallicity gradient in the galaxy ESO 138-G01. The near-constant ionisation parameters suggest that radiation pressure regulates the density structure of NLRs on multi-kiloparsec scales. The ionising radiation is measured to be harder in ionisation cones than elsewhere, but the results are sensitive to spectral contamination. We also consider mixing of NLR emission with emission from HII-regions in star-forming galaxies. A 'mixing' grid (combining HII and NLR model grids) is coupled with a statistically powerful sample from the Sloan Digital Sky Survey (SDSS) to constrain the HII-AGN 'mixing fractions' using NebulaBayes. It is found that for the majority of Seyfert-classified SDSS spectra, the majority of the Balmer emission arises in HII regions as opposed to NLRs. We also make the first systematic and robust measurements of the gas-phase metallicities of active galaxies in the SDSS. The metallicities associated with Seyfert-classified emission are shown to be consistently high and the SDSS AGN follow the upper locus of the SDSS stellar mass-metallicity relation.

Recent studies of neutral atomic hydrogen (HI) in nearby galaxies find that all isolated star-forming disk galaxies are HI saturated, in that they carry roughly as much HI fraction as permitted before this gas becomes gravitationally unstable. By taking this HI saturation for granted, the atomic gas fraction fatm of galactic disks can be predicted as a function of a stability parameter q ∝ j/M, where M and j are the baryonic mass and specific angular momentum of the disk (Obreschkow et al. 2016). The (logarithmic) difference ∆fq between this predictor and the observed atomic fraction can be seen as a physically motivated way of defining a ‘HI deficiency’. While isolated disk galaxies have ∆fq ≈ 0, objects subject to environmental removal of HI are expected to have ∆fq > 0. Within this framework, we revisit the HI deficiencies of satellite galaxies in the Virgo cluster and in clusters of the EAGLE simulation. We find that observed and simulated cluster galaxies are HI deficient and that ∆fq increases as we get closer to the cluster centres. Hence, the (q, fatm)-plane offers a practical diagnostic of environmental effects. The ∆fq values are found to be similar to traditional HI deficiency estimators. By tracking the simulated HI deficient cluster galaxies back in time, we confirm that ∆fq ≈ 0 until the galaxies first enter the cluster, at which moment they quickly lose HI by environmental effects. Finally, we use the simulation to investigate the links between ∆fq and quenching of star formation.

Galaxies at z~3.0 lie at an important juncture in the rise and fall of cosmic star formation density. The strong burst of star formation at z~3.0 is required to explain the appearance of massive galaxies with suppressed star formation rates at z<3.0. In this talk, I will present my resent results on the kinematics of star-forming galaxies at z~3 from MOSEL survey. We find that massive galaxies (Mstar > 10^10 Msun) at z~3.0 have lower velocity dispersion compare to the same stellar mass galaxies at z~2.0. Comparison with IllustrisTNG simulation indicates that mergers in galactic outskirts are responsible for a rapid rise in the dark matter content of massive galaxies between z=2-3. Our results suggest that strong dissipational processes such as mergers and disk-instabilities are driving the evolution of massive galaxies between z=2-3.

Intergalactic medium temperature is a powerful probe of the epoch of reionisation, as information is retained long after reionisation itself. However, mean temperatures are highly degenerate with the timing of reionisation, with the amount heat injected during the epoch, and with the subsequent cooling rates. We find that these degeneracies can be broken using the scatter in temperatures, allowing tighter constraints on reionisation timing. We post-process a suite of semi-analytic galaxy formation models to characterise how different thermal statistics of the intergalactic medium can be used to constrain reionisation. Temperature is highly correlated with redshift of reionisation for a period after the gas is heated. However, as the gas cools, thermal memory of reionisation is lost, and a power-law temperature-density relation is formed. Constraining our model against electron optical depth and temperature at mean density, we find favourable models with a late reionisation, finishing at a redshift of 6.5 with a soft UV spectral slope of 2.8.

Integral field spectroscopy with instruments such as MUSE provide an extraordinary dataset to study the resolved spatial and spectral properties of ionized HII regions in nearby galaxies. Having self-consistent stellar tracks and atmosphere modeling are crucial to accurately interpret observations of HII regions. To date, only a handful of stellar evolution models are available and they all use the same metallicity abundances. We know now that the assumed metallicity abundances greatly impacts the relative scaling of the lines ratios for the HII regions, and hence, the input elemental abundances will have a non-insignificant on the resulting parameters, such as metallicity, geometry, temperature, and ionization parameter. We now have empirical actual abundance sets that we use to create stellar models that are physically accurate and self-consistent with their stellar atmosphere modeling. We will present the impact of the different assumed elemental abundances has on the observable spectral energy distributions.

One of the principal systematic constraints on the Epoch of Reionisation (EoR) experiment using the Murchison Widefield Array (MWA) is the accuracy and depth of the foreground calibration and signal model. Given the large field of view of the MWA, the MWA EoR fields contain several bright, extended sources located either at the edges of the MWA primary beam or in the primary beam sidelobes. Recent results have shown that accurately modeling and removing bright sources at the edges of the field and in the sidelobes, removes more contaminating signal than just removing sources at the center of the primary beam. To improve the models of sources in the MWA primary beam sidelobes of the EoR0 and EoR1 fields, we are conducting the Long Baseline Epoch of Reionisation Survey (LoBES). This survey consists of multi-frequency (between 103 --230 MHz) observations of EoR0, EoR1, and their eight neighboring fields using the MWA Phase II extended array. These observations will provide high-resolution, uv-components to complement the existing uv-plane sampling of these fields. Additionally, observations of the neighboring fields will provide high-resolution observations of sidelobe sources within the center of the MWA primary beam, where the primary beam is well modeled. This talk will present the first results of LOBES for the MWA EoR1 field, a field that is of particular interest given the locations of both Pic A and Fornax A within the field's primary beam and sidelobes.

Studying extended radio source populations is challenging. Determining the host galaxy of these extended sources is usually a manual task, as the sources can have complex morphologies. We developed a machine learning model for radio-infrared cross-identification, trained this model on crowdsourced citizen science data from Radio Galaxy Zoo, and applied it to the VLA Faint Images of the Radio Sky at Twenty-centimeters (FIRST) survey. Our resulting catalogue of 157~007 radio sources and their infrared hosts is the largest sample of cross-identified radio sources ever. Using this catalogue, we estimate radio luminosity functions split by different host galaxy criteria: redshift, physical extent, and mid-infrared colour. We estimate the mechanical energy contribution of inferred active galactic nuclei jets to the inter-galactic medium. Our machine learning training methods, cross-identification approach, and radio luminosity function estimation method will be applicable to large upcoming surveys in the lead-up to the Square Kilometre Array. Such applications will boost the sample size even more and allow for even more detailed and precise radio luminosity functions.

In the near future, all-sky radio surveys are set to produce catalogues of tens of millions of sources with limited multi-wavelength photometry. Spectroscopic redshifts will only be possible for a small fraction of these new-found sources. In this talk, I provide the first in-depth investigation into the use of the k-Nearest Neighbours (kNN) algorithm for the estimation of redshift of these sources, comparing with Linear and Logistic Regression, and Random Forests. We use the Australia Telescope Large Area Survey (ATLAS) radio data, combined with the Spitzer Widefield InfraRed Explorer (SWIRE) infra-red, the Dark Energy Survey (DES) optical and the Australian Dark Energy Survey (OzDES) spectroscopic survey data. We then reduce the depth of photometry to match what is expected from upcoming Evolutionary Map of the Universe (EMU) survey, testing against both data sets. To examine the generalisation of our methods, we test one of the sub-fields of ATLAS against the other. We achieve an outlier rate of ~5%, showing that the kNN algorithm is an acceptable method of estimating redshift given an appropriate distance metric, and would perform better given a sample training set with uniform redshift coverage.

While a detection of the epoch of reionisation from the 21cm signal remains a few years away, ongoing experiments such as the MWA and LOFAR have recently published upper limits on the 21cm power spectrum amplitude. These new limits are now aggressive enough to begin to rule out interesting regions of astrophysical parameter space. Using 21CMMC, an MCMC sampler of 3D semi-numerical reionisation simulations I will explore which astrophysical models are disfavoured by the observational limits. Further, these limits arise only from small subsets of the existing observational data as such I will also discuss the future prospects as the MWA and LOFAR continue to improve their analysis pipelines and process more observational data.

For future deep imaging surveys, like DINGO, long-term visibility storage is desired to enable reprocessing and the mitigation of potential low-level systematic errors. However, due to the sheer volume of raw observational data generated, only compressed visibility storage is possible. DINGO will to use gridded visibilities to overcome the storage bottleneck. Gridded visibility storage enables data combination prior imaging, thus giving the option for improving final image quality, if needed, via `pixelated' processing steps equivalent of the traditional ungridded case, such as preconditioning, RFI flagging or continuum subtraction. However, such processing requires the development of new algorithms, and the testing and mitigation of any algorithmic errors introduced by the pixelated imaging methodology. We present the implementation of an initial gridded imaging pipeline, and the first results on simulated spectral line observations. We examine these results to assess the impact and magnitude of the introduced errors, and discuss potential solutions and implementation strategies. Our pipeline lays down the foundations of a new scientific data product and thus opens new possibilities for deep spectral line surveys on SKA and it's precursors.

We present an enhanced version of the multiwavelength spectral modeling code MAGPHYS that allows the estimation of galaxy photometric redshift and physical properties (e.g., stellar mass, star formation rate, dust attenuation) simultaneously, together with robust characterization of their uncertainties. The self-consistent modeling over ultraviolet to radio wavelengths in MAGPHYS+photo-z is unique compared to standard photometric redshift codes. The broader wavelength consideration is particularly useful for breaking certain degeneracies in color vs. redshift for dusty galaxies with limited observer-frame ultraviolet and optical data (or upper limits). We demonstrate the success of the code in estimating redshifts and physical properties for over 4,000 infrared-detected galaxies at 0.4 < z < 6.0 in the COSMOS field with robust spectroscopic redshifts. We achieve high photo-z precision, high accuracy (i.e., minimal offset biases, and low catastrophic failure rates over all redshifts. Interestingly, we find that a weak 2175A absorption feature in the attenuation curve models is required to remove a subtle systematic photo-z offset that occurs for dusty galaxies when this feature is not included. As expected, the accuracy of derived physical properties in MAGPHYS+photo-z decreases strongly as redshift uncertainty increases. The all-in-one treatment of uncertainties afforded with this code is beneficial for accurately interpreting physical properties of galaxies in large photometric datasets.

Stars with unusual elemental abundances offer clues about rare astrophysical events or nucleosynthetic pathways. Stars with significantly depleted magnesium and enhanced potassium ([Mg/Fe] < −0.5; [K/Fe] > 1) have to date only been found in the massive globular cluster NGC 2419 and, to a lesser extent, NGC 2808. The origin of this abundance signature remains unknown, as does the reason for its apparent exclusivity to these two globular clusters. In this talk I present data from 112 field stars - identified out of 454,180 LAMOST giants - that show significantly enhanced [K/Fe] and possibly depleted [Mg/Fe] abundance ratios. The sample spans a wide range of metallicities (−1.5 < [Fe/H] < 0.3), although none show abundance ratios of [K/Fe] or [Mg/Fe] that are as extreme as those observed in NGC 2419. Our findings suggest that the nucleosynthetic process producing the anomalous abundances ratios of [K/Fe] and [Mg/Fe] occurs at a wide range of metallicities. I will also discuss the implications of our analysis, arguing that the spread in metallicity in our data means that pollution scenarios limited to early epochs (such as Population III supernovae) are unlikely to be responsible for this abundance signature.

The star formation history of the universe reveals that galaxies most actively build their stellar mass at cosmic noon, roughly 10 billion years ago, with a decrease toward present-day. The resulting metal-enriched material ejected from these galaxies due to supernovae and stellar feedback is deposited into the circumgalactic medium (CGM), which is a massive reservoir of diffuse, multiphase gas out to radii of $\sim200$~kpc. The CGM is the interface between the intergalactic medium and the galaxy, through which accreting filaments of near-pristine gas must pass to contribute new star formation material to the galaxy, and outflowing gas is later recycled. Simulating these baryon cycle flows is crucial for accurately modeling galaxy evolution. We examine these multiphase CGM gas flows with the quasar absorption line technique, primarily focusing on the low-ionization MgII absorption doublet (T$\sim10^{4}$~K), with additional multiphase ions such as Lyman alpha, FeII, and CIV. With the combination of HST images, high-resolution UVES/VLT quasar spectra, and cutting-edge IFU data from the Keck Cosmic Web Imager, we quantify the gas kinematics and metallicities of outflowing gas at 69 kpc along the minor axis of an edge-on ($i=85^{\circ}$) galaxy at cosmic noon ($z_{\rm gal}=2.070$). Connecting these results to our Multiphase Galaxy Halos Survey at $z\sim0.3$, we study the evolution of CGM kinematics and metallicities over nearly 10 billion years.

The measurement of the cosmic 21-cm signal with the SKA will transform our understanding of the epochs of reionization and cosmic dawn. The properties of the first stars and galaxies are encoded in the patterns of the signal. Interpreting these patterns requires accurate and efficient models. I will present an update of the 21cmFAST semi-numerical simulation, which separately accounts for star-formation inside the very first galaxies. This unseen and transient population of galaxies obtain their gas through molecular cooling from the intergalactic medium, and could have markedly different properties from the more massive galaxies observed with Hubble and eventually JWST. I demonstrate that if the recently-reported EDGES signal at z~17 is genuinely cosmological, these molecularly-cooled “mini-halo” galaxies must have played a dominant role during Cosmic Dawn.

Pulsars in binaries with neutron stars or pulsars form one of the most exciting astrophysical systems observed. Not only do they allow tests of General Relativity for the strong gravity regime, or act as high accuracy clocks, their merger can produce gravitational waves detectable by current ground based and future space based GW detectors. For predicting and studying the properties of such binaries detailed modeling of their populations are required. We model the population of Galactic double neutron stars using the population synthesis code COMPAS, including a model for the evolution of the pulsar parameters (spin period and magnetic field). We compare the observed double neutron star population to our models, accounting for radio selection effects. Our suite of models show broad agreement with the observed properties of Galactic double neutron stars. We highlight the physical assumptions to which our models are most sensitive. We also use these models to predict the masses and spins of neutron stars which will be observed in gravitational-waves.

Polarisation observations of pulsars, facilitated by SKA precursor/pathfinder radio telescopes, provide insightful probes of astrophysical plasmas. For example, measuring (and monitoring) dispersion and Faraday rotation measures elucidates the ISM electron density and magnetic field strength and direction parallel to each line of sight. I will highlight recent results from LOFAR and Parkes, which provide an estimate of the magnetic scale height in the Galactic halo, and a characterisation of small-scale turbulent structures in the Vela supernova remnant, respectively.

The Maunakea Spectroscopic Explorer is a future observatory and survey project that will bring highly multiplexed spectroscopy to a 10m-class telescope. The science case for MSE is broad, and ranges from dark matter and neutrino cosmology to galaxy evolution, exoplanets and stellar astrophysics. I will describe the plans for MSE studies of the Milky Way and resolved stellar populations in the Local Group. MSE will carry out the ultimate spectroscopic follow-up of the Gaia mission, and conduct in situ chemodynamical analysis of individual stars across all Galactic components. It will gather spectra for an order of magnitude more stars in Local Group dwarf galaxies across the full luminosity range ($10^{3} - 10^{7} L_{\odot}$) and enable the chemo-dynamical deconstruction of M31 and M33 across their entire spatial extent.

Changing Look AGN (CLAGN) are quasars whose emission lines change from broad to narrow or vice versa. Since these changes appear to occur on timescales of a few years or less, there has been considerable interest in the physical processes which might cause such changes. We present a sample of CLAGN discovered during the SkyMapper Southern Survey, highlighting the value of all-sky surveys for time domain astronomy. We then consider to what extent Supernovae IIn could explain some of the CLAGN cases.

One part of the Australian Dark Energy Survey was the observation of nearly 800 Active Galactic Nuclei, with the aim to measure the mass of the central supermassive black holes. By measuring the time lags in the AGN disks, AGN can be turned into standardisable candles, allowing us to determine distances in the Universe far beyond what is currently possible using supernovae. We find that the current OzDES spectroscopic cadence (approximately monthly) poorly samples the emission-line light curves of the lower luminosity AGN at z < 1. This is a critical limitation as these sources anchor the calibration of high-z AGN as cosmological distance probes, and overlap with the region where type Ia supernova measurements are abundant, allowing cross-probe analysis. I will present results showing the impact of cadence on AGN light-curves and subsequent measurements, and how this can be fixed for future facilities and surveys such as SDSS-V and LSST.

Over a dozen new stellar streams in the halo of the Milky Way have been discovered in the southern hemisphere with the Dark Energy Survey (DES) in recent years, with other datasets yielding additional stellar substructure. To study these we have embarked on an ongoing spectroscopic program, S5, which has been mapping these southern streams with 2df+AAOmega on the AAT. An international collaboration, S5 is the first systematic program pursuing a complete census of known streams in the southern hemisphere. The radial velocities and stellar metallicities from S5 - together with proper motions from Gaia DR2 - provide us with a unique dataset for understanding the stellar populations of the Milky Way's halo, the progenitors and formation processes of the streams, the mass and overall morphology of the Milky Way's gravitational potential, and ultimately potential clues to the nature of dark matter. Thus far, the S5 program has obtained 6D+1 phase space information for 10 streams in the DES footprint, all of which are the first such measurements for these southern streams, and we now are expanding our program beyond the DES footprint to cover more southern streams. I will give an overview of the S5 program, including target selection, observation, and data analysis, and I will finish with a discussion of the early science results from S5.

A galaxy’s angular momentum is a fundamental property in its evolutionary history, as it encodes the impact of cumulative tidal torques over its lifetime. Together with stellar mass, angular momentum regulates disk thickness and colour, dictates star formation efficiency, and predicts morphology. The mean specific angular momentum j of the baryons agrees with the dark matter halo, but the probability density functions (PDFs) differ due to further physical processes: baryonic material with low j is ejected by AGNs and stellar winds, while high-j material is removed by tidal stripping. In this talk I will demonstrate that the galaxy stellar specific angular momentum distribution is a robust tracer of morphology via higher-order moments of the PDF(j). Galaxies with bigger bulges have more strongly-tailed PDF(j)s due to an excess of dispersion-dominated material, while disks of all sizes rotate similarly. However, the PDF(j) is not well-described by theoretical predictions for well-ordered rotating disks and dispersion-dominated bulges. Finally I will present the utility of the PDF(j) as a photokinematic decomposition tool, encoding more physical information than photometry or kinematics alone.

In the past five years, the number of known double neutron stars (DNS) in the Milky Way has roughly doubled. We argue that the observed sample can be split into three distinct sub-populations based on their orbital characteristics: (i) short-period, low-eccentricity binaries; (ii) wide binaries; and (iii) short-period, high-eccentricity binaries. These sub-populations also exhibit distinct spin period and spindown rate properties. We focus on sub-population (iii), which contains the Hulse-Taylor binary. Contrary to previous analysis, we demonstrate that, if they are the product of primordial binary evolution, the second-born NSs in these systems must have been formed with small natal kicks (<25 km/s) and have pre-SN masses narrowly distributed around 3.2 solar masses. These constraints challenge binary evolution theory. Motivated by the similarity of these DNSs to B2127+11C, a DNS residing in the globular cluster M15, we argue that this sub-population is consistent with being formed in, and then ejected from, globular clusters. This scenario provides a pathway for the formation and merger of DNSs in stellar environments without recent star formation, as observed in the host galaxy population of short gamma ray bursts and the recent detection by LIGO of a merging DNS in an old stellar population.

17th of August 2017 was a great day for multi-messenger astronomy when the two LIGO detectors detected the inspiral signal from the merger of a binary neutron star system [1]. The advanced VIRGO detector aided the localisation of this system in the sky thereby allowing astronomers to look at a precise patch in the sky to perform electromagnetic follow up of the source. While this event allowed us to gleam an insight into short gamma-ray bursts, neutron star mergers, jet formation and topology, r-process nucleosynthesis [2] but information about the merger and post-merger phases of the system are still unknown to us. These parameters can be obtained around the actual merger, and occur in the 1 kHz to 5 kHz regime. A gravitational wave detector engineered to focus on these signal frequencies would allow us to probe the exotic nuclear physics in the cores of neutron stars in a regime not accessible with the current terrestrial experiments [3]. This science case has prompted a design study focussed on a high frequency Australian gravitational wave detector , OzHF . In addition to the current technology, new technology that builds on the Australian research strength will be developed for the same which will be suitable for future third generation detectors planned around the world. The design concept is based on an advanced LIGO like detector, with a dual recycled Fabry Perot Michelson interferometer with squeezed light technology, Silicon test masses and cryogenic suspensions all of which would allow a competitive strain [4] sensitivity of 1x10-25 /√Hz between 1-5 kHz all with relative short Michelson arm lengths. References : [1] LIGO Scientific Collaboration and Virgo Collaboration , “GW150914: The Advanced LIGO Detectors in the Era of First Discoveries”. Phys. Rev. Lett., 116:131103, Mar 2016. [2] B. P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration), “GW170814: A Three-Detector Observation of Gravitational Waves from a Binary Black Hole Coalescence”, Phys. Rev. Lett. 119, 141101 [3] OzHF, paper in preparation [4] Evans, M & Harms, Jan & P. Abbott, B & Abbott, Randy & Abbott, Thomas & Abernathy, Matthew & Ackley, K & Adams, C & Addesso, Paolo & X. Adhikari, R & Adya, Vaishali et.al. (2016). Exploring the Sensitivity of Next Generation Gravitational Wave Detectors. Classical and Quantum Gravity. 34. 10.1088/1361-6382/aa51f4.

The Small Magellanic Cloud (SMC) at only 1/5 solar metallicity is the only galaxy near enough to study the effect of a low metallicity environment on the physics of star formation and the ISM on small spatial scales. Understanding the effects of low metallicity is crucial for understanding galaxies in the early universe and the evolution of galaxies over cosmic time. Initial ALMA observations in the SMC show similar compact CO clumps (Jameson et al. 2018), but only small areas targeting specific star-forming regions have been mapped to date and we lack a statistically significant sample of the CO structure throughout the galaxy. We used ALMA in ACA standalone mode to map a 1.0 deg x 0.5 deg (~1 kpc x 500 pc) area of the Southwest Bar of the SMC at ~6.5” resolution and cover an unprecedented range in size scales from ~1.5 pc to 1 kpc. Our new map shows previously undetectable small (~ pc) molecular gas clumps, similar to what is seen in WLM (Rubio et al. 2015) and NGC 6822 (Schruba et al. 2017), but across a much larger scale. I will discuss the properties of the CO-emitting gas and how it compares to the HI gas from our new ATCA HI absorption survey and GASKAP HI map and what that reveals about the atomic-to-molecular transition at low metallicity.

The chemical evolution of the Universe is governed by the nucleosynthesis contribution from stars, which in turn is determined primarily by the initial stellar mass. Elements heavier than iron are predominantly formed by neutron captures, where two main processes are theorised to be responsible: the slow and rapid processes. The rapid processes likely occurs in merging neutron stars but may occur in other explosive sites as well. In contrast, the slow neutron capture process is mostly made in evolved low and intermediate mass stars. In this talk I present new predictions for the slow neutron capture process, with an emphasis on exploring uncertainties. The new yields are used in an updated Galactic chemical evolution (GCE) model for all elements from carbon to uranium based on the work of Kobayashi et al. (2011). I describe this model and discuss results. The new predictions a good match for observations of some heavy elements (e.g., strontium) but not others (e.g., an overproduction of barium). I finish with a discussion of possible solutions.

The population properties of compact binaries—such as their merger rates, mass spectrum, and spin distribution—can be inferred from unresolved, sub-threshold signals that form the astrophysical gravitational-wave background. This enables redshift ≈ 2 cosmology with the current generation of ground-based gravitational-wave observatories. The reconstructed distributions of unresolved binaries may be compared to the distribution of nearby, resolved binaries, enabling us determine how population properties have evolved over the course of cosmic time. By expanding our analysis to include both resolved and unresolved events, we eliminate bias from selection effects. Simultaneously, we provide a unified framework for rate and population inference using compact binary detections and measurements of the gravitational-wave background.

The role played by magnetic fields is a key missing piece of the puzzle in the evolutionary picture of radio galaxies. These sources play a crucial role in driving the evolution and chemical make-up of the Universe, through (for example) feedback processes and mixing of gas. The largest radio galaxies - known as giant radio galaxies (GRG) - typically reside in poor clusters or groups of galaxies, and are thought to trace the warm-hot intergalactic medium (WHIM), the tenuous medium that is thought to comprise much of the missing baryon fraction of the Universe. As such, polarisation studies of GRG can be used to probe the magnetic field configuration of the large-scale structure of the Universe. ESO 422-G028 is one such GRG. In the POlarised GLEAM Survey (POGS), ESO422 was found to exhibit low-frequency polarisation properties that imply complex underlying physics, indicative of interaction with the ambient medium. In this talk, I will present the results of our subsequent observing campaign on ESO422, involving the first joint study with the full 36-dish Australian Square Kilometre Array Pathfinder (ASKAP) and the expanded Phase II Murchison Widefield Array (MWA), as well as ultra-deep data from the Australia Telescope Compact Array (ATCA). This campaign has provided a unique broad-band full-polarisation dataset spanning the frequency range 88 MHz to 35 GHz. The spectral properties of the diffuse radio emission strongly suggest multiple epochs of AGN activity, while the polarisation properties provide further evidence of rich physics, suggesting a magnetic “cocoon” on the surface of the lobes. This broad-band dataset also allows us to probe the physics of the host galaxy and jets in unprecedented detail for a mJy-level radio source, two orders of magnitude fainter those discussed in previous studies.

A full understanding of how the environment affects star formation in galaxies is yet to be realised. A key hindrance here is that environmental interactions modulate galaxy star formation in a spatially non-uniform way whereas, until recently, large galaxy surveys that enable galaxy demographic studies have relied on single, unresolved spectra. I will present recent results from the SAMI Galaxy Survey, which provides resolved spectroscopy for more than 3000 galaxies spanning a range in environments from the low-density field, to the dense cores of rich galaxy clusters. Using the SAMI data, we have identified a rare population of galaxies that harbour localised regions with very young stellar populations (<1.5Gyr) in the absence of current star-formation. This signature indicates that these galaxies are in the process of having their star-formation quenched, and are in a transition phase. I will highlight key differences between the transition galaxies found in the dense cluster environments and those found in lower density regions. In particular, we use the resolved data provided by SAMI, along with the exquisite ancillary data, to show that the cluster transition galaxies are currently being quenched by ram pressure stripping on their first passage through the cluster. I will also discuss how the next generation Hector Galaxy Survey will help us understand the future evolution of these transition galaxies.

Early type binary systems often show phase dependent linear polarisation variations with two peaks and troughs in an orbital cycle. In the past this has usually been interpreted as due to scattering from circumstellar gas. We show that the actual dominant mechanism is light reflected from each star reflected off its companion. We are investigating the use of this effect to measure binary inclinations and hence masses for non-eclipsing systems. It may also be a way of detecting previously unknown binary systems.

Radio interferometers have collected vast amounts of low-frequency data in order to detect the structure of the Epoch of Reionization in the 21\,cm power spectrum. While we are no longer data-limited, lower limits are still orders of magnitude above expected EoR levels. We discuss the future of the EoR field, and the potential limitations that culminate in a lower limit plateau. In our newest MWA data analysis, we address these subtle systematics to measure the lowest EoR structure limit thus far: $\Delta^2 \leq (47\,$mK)$^2$ at $k=0.23$\,\textit{h}\,Mpc$^{-1}$ and $z=7$. While our effects are presented within an MWA-specific framework, they have repercussions to any general instrument and imaging power spectrum analysis.

We are currently living in the era of big stellar galactic surveys that aim at reconstructing the history of the Milky Way. One of their most important assumptions is that stars born in the same group are chemically homogenous. At what level can this assumption be supported by observations? To date, several important tests have confirmed that unevolved stars in open clusters are chemically homogeneous at the level of the measurement uncertainties, typically the 15% of the elemental abundances. Nevertheless, recent controlled experiments using twin stars have revealed underlying chemical inhomogeneities that may limit our capability of chemical tagging at higher precision. In this talk I will review the results of these studies and investigate the possible origins of the chemical anomalies.

Students in large lecture classes often indicate that they lack a sense of community within their universities. The creation of collaborative groups is one way to address this concern, but many instructors are unsure whether collaborations actually improve understanding. We will discuss results of a two-year study to gauge the impact of collaborative two-stage exams on student learning and attitudes in university-level introductory astronomy classes for non-science majors. In the collaborative two-stage exam setting, students first completed an exam individually, and then they retook a portion of that exam within their previously established groups. During the collaborative phase, students were free to discuss the questions with their peers and arrive at a common answer. Students took three to four exams during the semester using this format. At mid-semester, we surveyed the students to gauge their attitudes about collaborative work and its perceived influence on their exam preparation and performance. At the end of the semester, students sat an individual-only final exam, which contained all previous questions from the collaborative phase, as well as a subset of questions seen only on the individual portions. When we compare student performance on final exam questions that were included in the collaborative portions to those found in only the individual portions, we find generally higher student performance for questions encountered on the collaborative portions of the exams. The opportunity to work as a group was reported by students to have a positive influence on their overall learning and their study habits. **CO-PRESENTERS: C. Renee James and Scott T. Miller

Internationally, many countries are extremely concerned about the low levels of STEM participation and expertise, particularly from females and those with disadvantaged socioeconomic backgrounds. Simultaneously, there are various excited but time consuming research projects that the scientific community would like to pursue. In the Original Research By Young Twinkle Students (ORBYTS) program, we aim to tackle both of these goals by creating an environment in which small teams of high school students work with a doctoral or post-doctoral researcher to undertake original scientific research, ideally contributing to a publication in the peer-reviewed literature (4 are currently published with student co-authors). This project simultaneously fulfils many outreach, training and research objectives. It is particularly notable for allowing junior researchers the opportunity to supervise, direct and manage a research project and research team. ORBYTS started in the UK, but has now expanded internationally, including in Australia with pilot programmes. I will discuss the history of research-in-schools programmes, the challenges and opportunities of these programmes, and highlight exciting opportunities in the Australian context that I am starting to explore and pilot.

The IceCube Neutrino Observatory at the South Pole has started the field of neutrino astronomy, recording many hundreds of neutrinos from the distant Universe. In 2018, IceCube revealed that a distant blazar, TXS0506+056, is likely the first identified high-energy neutrino source. This discovery came from a multi-messenger campaign, where an IceCube neutrino alert was followed-up by other observatories, which saw high activity in gamma-rays. Together, these observations suggest a common origin of the neutrinos and gamma-rays following particle acceleration in the jet, and subsequent interaction, where the produced pions decay to yield the observed neutrinos and gamma-rays. In this talk I will discuss how this discovery was made, the astrophysical implications, and the prospects for a future expansion of IceCube, to further enhance its neutrino astronomy capabilities.