# Posters

All posters will be displayed for the duration of the meeting. They will be located in Room 7-207.

### P1 - A new method for rapid stellar evolutionPoojan AGRAWAL, Swinburne University of Technology

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.

### P2 - Study of Optical Hα and TeV Sources detected by H.E.S.S. as Possible Physical Phenomena.Rami ALSULAMI, The University Of Adelaide

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.

### P3 - Dispersion Measure - Redshift Relation from the EAGLE simulationsAdam BATTEN, Swinburne University of Technology

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.

### P4 - Gone with the wind: searching for signatures of gas removal in environmentally perturbed galaxiesTaylah BEARD, Macquarie University

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.

### P5 - Constraining high energy particle interaction properties and extending the gamma ray observations to beyond PeV energies with CTA telescopesJose BELLIDO, The University of Adelaide

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.

### P6 - Bayesian Model Selection with Future 21cm Observations of The Epoch of ReionisationThomas BINNIE, Imperial College London

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.

### P7 - Galactic Centre Case Studies with Mopra Carbon Monoxide DataRebecca BLACKWELL, University of Adelaide

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.

### P8 - Determining the spatio-kinematic structures of jets in post-AGB binariesDylan BOLLEN, Macquarie University

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.

### P9 - Carbon Depletion on the Red Giant Branch with APOKASCChris BROCKETT, University of New South Wales

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.

### P10 - Neutrino Astronomy with IceCube: blazar neutrino observation and future upgrade and expansion plansRyan Thomas BURLEY, The University of Adelaide

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.

### P11 - Astronomy and Space at Queensland’s Mt Kent ObservatoryBradley Darren CARTER, University of Southern Queensland

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.

### P12 - SkyMapper follow-up program of gravitational wave events in LIGO/Virgo O3 runSeo-Won CHANG, Australian National University

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.

### P13 - An improved hidden Markov model search for continuous gravitational waves from Scorpius X-1Patrick CLEARWATER, The University of Melbourne

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.

### P14 - Using graphical processing units to achieve order of magnitude speedups in continuous gravitational wave searchesPatrick CLEARWATER, The University of Melbourne

For many continuous gravitational wave (GW) searches, computational cost is the bottleneck limiting the sensitivity achieved and parameter space covered. For example, the $\mathcal{F}$- and $\mathcal{J}$-statistics are used to search for GWs from neutron stars in isolated and binary systems, respectively, and must be calculated for many billions of search parameters to search for a particular target. Graphical processing units (GPUs) are widely used, in astronomy and beyond, for speeding up massively-parallel algorithms. We show that by porting the $\mathcal{F}$- and $\mathcal{J}$-statistics from CPU to GPU -- as well as carefully implementing the algorithm to best exploit the GPU’s parallelism and memory architecture -- we can achieve order-of-magnitude speedups. This feeds into an increase of similar magnitude in parameter space covered by a search, enhancing prospects for gravitational wave discovery.

### P15 - Evolution of the Relative Black Hole-Galaxy Growth in Milky Way and Andromeda-mass ProgenitorsMichael COWLEY, University of Southern Queensland

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.

### P16 - Stromlo Student Seminars 2019Lara CULLINANE, The Australian National University

The Australian National University Research School of Astronomy and Astrophysics will be hosting its annual Student Seminars this November! This two-day conference is designed to be a fun and relaxed event for astronomy and astrophysics research students from all over Australia. The event will give late stage undergraduate and postgraduate students the chance to network with peers (and future colleagues), practise public speaking skills, and learn about the breadth of research happening around the country. Each year the Student Seminars has a theme, which can be incorporated into talks; or could even be the focus of a talk itself. All students are invited to join us for this exciting event.

### P17 - Localising Fast Radio Bursts with ASKAPAdam DELLER, Swinburne University of Technology

With a real-time detection system coupled to a voltage data buffer, the ASKAP telescope is capable of not just detecting Fast Radio Bursts, but also studying them in unprecedented detail. By saving antenna voltages, offline correlation can be performed, allowing the FRB to be 1) localised to sub-arcsecond precision and associated with a host galaxy, and 2) coherently de-dispersed and studied in full polarisation at the highest time resolution. I will present early results of the CRAFT survey on ASKAP, covering both the scientific results, and the lessons learned that are applicable to similar searches using the SKA.

### P18 - A metallicity map of the Small Magellanic Cloud using near-infrared passbands of the VMC VISTA Survey.samyaday CHOUDHURY, MACQUARIE UNIVERSITY

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.

### P19 - Group pre-processing vs. cluster ram-pressure stripping: the case of ESO156-G029Robert DZUDZAR, Swinburne University of Technology

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.

### P20 - Detecting gravitational waves from a binary neutron star post-merger remnant.Paul EASTER, Monash University

The detection of gravitational waves from the inspiral of binary neutron stars may soon become common place. As yet, no detection of gravitational waves from the post-merger remnant has occurred. Numerical relativity simulations allow us to model gravitational waves of the hot remnant – although these are computationally expensive. We investigate using fast, analytical models based on numerical relativity output, to detect post-merger remnants.

### P21 - Generating Mock Galaxy Images for the Huntsman TelescopeAmir EBADATI BAZKIAEI, Macquarie University

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

### P22 - The Cherenkov Telescope ArraySabrina EINECKE, The University of Adelaide

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.

### P23 - The Dawn of Extreme Gamma-Ray AstronomySabrina EINECKE, The University of Adelaide

With the recent upgrades to HESS and forthcoming CTA gamma-ray observatory, we are now in a position to study the Universe at extreme gamma-ray energies reaching 100 TeV and beyond. With such gamma rays we can being to directly probe the Milky Way's highest energy cosmic-ray particle accelerators exceeding 1 PeV. These so-called "PeVatrons" represent our Galaxy's extreme accelerators. One of the most promising ways to look for PeVatrons is via cosmic rays escaping supernova remnants and interacting with the neighouring interstellar medium. This poster will outline our plans to use HESS and the first CTA telescopes to probe such objects in the hunt for these PeVatrons, and include some preliminary modeling of source candidates.

### P24 - The Interstellar Medium Towards the Mysterious Unidentified Gamma-Ray Source HESS J1804-216Sabrina EINECKE, The University of Adelaide

The High Energy Stereoscopic System (HESS) has discovered numerous Galactic TeV gamma-ray sources. HESS J1804-216 is one of the brightest and most mysterious sources discovered and is currently classified as an unidentified source, as no clear counterpart has yet been identified. It is vital to have an understanding of the gas surrounding a source as it can lead to constraining the nature of the source. The morphology of interstellar gas which surrounds HESS J1804-216 is investigated using data from the Mopra Southern Galactic Plane CO Survey and Southern Galactic Plane Survey (SGPS) of HI. Both the hadronic and leptonic scenarios of gamma-ray production are considered here.

### P25 - KM3NeTMiroslav FILIPOVIC, Western Sydney University

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).

### P26 - MEASUREMENTS OF B-MODE POLARIZATION OF THE COSMIC MICROWAVE BACKGROUND FROM 500 SQUARE DEGREES OF SPTPOL DATANikhel GUPTA, School of Physics, University of Melbourne

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 $\ell > 300$.

### P27 - In search of massive compact spheriod in local UniverseSuei Hei (Dexter) HON, Swinburne University of Technology

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.

### P28 - Electron density in different environments at redshift 1.6Anishya HARSHAN, UNSW-Sydney

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.

### P29 - Joint gravitational wave - gamma-ray burst detection rates in the aftermath of GW170817Eric HOWELL, ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav), University of Western Australia

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

### P30 - Identifying mergers in the white dwarf populationAdela KAWKA, International Centre for Radio Astronomy Research, Curtin University

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.

### P31 - Elastic Crust of a Neutron StarAlex KERIN, University of Melbourne

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).

### P32 - Towards a Cherenkov Telescope RingSimon LEE, The University of Adelaide

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.

### P33 - Collective vortex motion and neutron star glitchesJack LONNBORN, University of Melbourne

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.

### P34 - Dendrograms made easy: A story about how tree diagrams can help us understand star formation in our Milky Way GalaxyJohn Alexander Pena LOPEZ, University of New South Wales, Sydney

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.

### P35 - ATCA and ASKAP Catalogue of Radio Sources in the SPT-Spitzer Deep FieldPerica MANOJLOVIC, Western Sydney University

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.

### P36 - Challenging stellar evolution models with lithium-rich giant stars in the GALAH surveySarah MARTELL, University of New South Wales

A small fraction of evolved stars have high surface abundances of lithium, which is surprising because lithium should easily be destroyed during the transition from the main sequence to the red giant branch. Proposed explanations for this lithium enrichment have included planet ingestion, as well as internal mixing driven by rotation, the helium flash, and binary interactions. The GALAH survey contains approximately 2000 candidate lithium-rich giant stars. I will describe the orbital and stellar populations properties of these stars, and explore how we can use that information to test literature models for lithium enrichment.

### P37 - Upper limits on TeV gamma-ray emission from core-collapse supernovae observed with H.E.S.S.Nigel MAXTED, University of New South Wales Canberra at Australian Defence Force Academy

~kyr-age supernova remnants are widely considered to be prime suspects when investigating the origin of the Galaxy’s GeV-PeV cosmic ray proton population. Young supernovae (ages of days-months), however, also have the potential to accelerate protons up to PeV energies. The acceleration mechanism requires that the explosion impacts a dense circumstellar medium created by a high mass-loss progenitor star. Using the H.E.S.S. telescope, we searched for the TeV gamma-ray emission that would follow such particle acceleration in a sample of 10 extragalactic type II supernovae, most of which were serendipitously observed. No significant TeV gamma-ray emission was detected from the sample, allowing us to place model-dependent upper limits on the progenitor star mass-loss rates, generally in the range 2*10^-5 to 2*10^-3 solar masses/yr . Prospects for detecting gamma-ray emission from young extragalactic supernovae with the upcoming Cherenkov Telescope Array (CTA) look promising. A TeV gamma-ray signal from an extragalactic supernova would prove that sudden, short-duration cosmic ray acceleration could supplement the Milky Way cosmic ray population.

### P38 - Characterising the interstellar medium with the column density probability distribution functionShannon MELROSE, UNSW Sydney

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.

### P39 - Joint search for X-ray pulsations and gravitational wavesPatrick MEYERS, University of Melbourne

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.

### P40 - Searching for the stochastic gravitational-wave background in Advanced LIGO's first two observing runs and beyondPatrick MEYERS, University of Melbourne

The observation of gravitational waves (GWs) in mergers of binary black hole and binary neutron star systems have helped to establish constraints on the rate of such mergers across the history of the Universe. These constraints can be used to estimate the amplitude of an astrophysical stochastic GW background from a superposition of such sources. Recently, estimates of the potential anisotropy of such a background have also been made and represent a target for third generation instruments. In this talk, I will discuss results from the recent searches for an isotropic and anisotropic stochastic gravitational-wave background that include data from Advanced LIGO’s first two observation runs. I will discuss how those limits compare to current theoretical estimates, as well as prospects for detection in the coming years as sensitivity improves and as we add detectors like Advanced Virgo to the network.

### P41 - Improving Bayesian Reconstructions of Gravitational-wave BurstsHannah MIDDLETON, University of Melbourne

(Author: Meg Millhouse) Abstract: The LIGO-Virgo collaboration uses a variety of techniques to detect and characterize gravitational waves. One approach is to use templates - models for the signals derived from Einstein’s equations. Another approach is to extract the signals directly from the coherent response of the detectors in LIGO-Virgo network. Both approaches played an important role in the first gravitational wave (GW) detections. Here we extend the BayesWave analysis algorithm, which reconstructs gravitational wave signals using a collection of continuous wavelets, to use a generalized wavelet family, known as chirplets, that have time-evolving frequency content. Since generic GW signals have frequency content that evolves in time, a collection of chirplets provides a more compact representation of the signal, resulting in more accurate waveform reconstructions, especially for low signal-to-noise events, and events that occupy a large time-frequency volume.

### P42 - Inference on the massive black hole binary population from pulsar timing array searches for gravitational wavesHannah MIDDLETON, University of Melbourne

Massive black holes reside at the centre of most galaxies. During galaxy mergers, the massive black holes at the centres of each galaxy are believed to form binaries, which can emit gravitational waves in the nano-Hertz frequency band. Pulsar timing arrays are being used to search for the gravitational wave background from many massive binary black hole binaries throughout cosmic time. No detection has yet been made, however pulsar timing arrays are placing upper limits on the strength of the gravitational wave background from these sources. As upper limits improve with sensitivity, we can make comparisons to astrophysical models of the population of massive black hole binaries. A lack of detection could indicate that either these binaries stall before reaching gravitational wave emission or are accelerated through the band. Using Bayesian hierarchical modeling we consider implications of this upper limit for a range of astrophysical scenarios, without invoking stalling, nor more exotic physical processes (Nat. Comm 9, 537, 2018). We find these models to be consistent so far, however as sensitivity improves the most optimistic predictions will become disfavored.

### P43 - Searching for continuous gravitational waves from low mass x-ray binaries with known neutron star rotation frequenciesHannah MIDDLETON, University of Melbourne

Ground-based gravitational wave observatories are searching for continuous gravitational waves from rotating neutron stars. One of the key targets for this search is Scorpius X-1, the brightest low mass x-ray binary (LMXB). Searches for Scorpius X-1 face some challenges. One of these is that unfortunately, electromagnetic observations of the binary have not been able to measure a rotation frequency for the neutron star. However, there are other LMXBs where the frequencies (and also the orbital parameters) are measured to high precision. Another challenge is that the rotation frequency itself may not be monochromatic and in fact wander slowly over time. A hidden Markov model can be used to search for just such a wandering frequency. Here we present on the design of a search for continuous gravitational waves from a number of LMXB targets with known neutron star rotation frequencies using data from the second observing run of Advanced LIGO (Laser Interferometer Gravitational-wave Observatory).

### P44 - Do Gains in Secondary Teachers’ Content Knowledge Provide an ASSET to Student Learning?Scott MILLER, Sam Houston State University

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.

### P45 - A search of Milky Way halo stars with globular cluster-like abundance patterns in GALAH surveyMohd Hafiz MOHD SAADON, The University of New South Wales

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.

### P46 - Searches for transients in GOTO difference images with an Artificial Neural NetworkYik Lun MONG, Monash University

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).

### P48 - Photometric and spectroscopic monitoring, radial velocities and evolutionary status of chromospherically active, close eclipsing binariesDavid Joseph Wulstan MORIARTY, The University of Qld.

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.

### P49 - Predictions of infrared excess and cosmic star formation rate density from UV constraints at z ~ 4 - 7Yisheng QIU, University of Melbourne

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 .

### P50 - Constraining the Dying Radio-Loud AGN PhaseBenjamin QUICI, Curtin University of Radio Astronomy

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.

### P51 - Low-frequency spectral variability of peaked-spectrum sourcesKathryn ROSS, Curtin University

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.

### P52 - Creating a global community for the use of Robotic Telescopes in Student Research and EducationSaeed SALIMPOUR, Deakin University/Edith Cowan University

This poster highlights the establishment and continuing development of a community to facilitate the exchange of information between astronomers, science educators. The Robotic Telescopes and Student Research and Education conference aims to provide a global picture of the role scientific research, technical engineering and astronomy education play in student research and education. The focus is on building a sustainable community around the educational, technical and student research uses of robotic telescopes, from small through to large aperture and from radio through to gamma-ray and involving both observed and archival data. It aims to be a meeting place for astronomers, teachers, educators, outreach practitioners, researchers, and observatory and telescope network developers and managers, in a continuing effort to share and combine resources, develop and enhance education and research programs, and foster global conversations and collaborations. It facilitates the storage of knowledge in the field through it’s yearly dual-peer-reviewed proceedings journal, RTSRE Proceedings and an astronomical journal, Astronomy, Theory, Observations and Methods.

### P53 - Stellar Population Gradients of SAMI Central and Satellite GalaxiesGiulia SANTUCCI, University of New South Wales

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.

### P54 - The GALAH Survey: Chemical tagging globular clusters to stellar streamsJeffrey SIMPSON, University of New South Wales

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

### P55 - A step in the radial metallicity distribution of the Galactic diskLorenzo SPINA, Monash University

The current big stellar galactic surveys are giving us the opportunity to substantially expand our knowledge of the history of our Galaxy. One of the key open questions in Galactic archeology regards the formation and evolution of the Galactic disk. Several hypothetical scenarios have been proposed to explain the chemo-dynamical properties of its stellar populations and the intimate nature of the thin and thick disks is still a topic of debate. We have used information on the chemical composition and astrometry of thin disk stars to unveil a step-like abrupt decrease in metallicity located at 9 kpc from the Galactic centre. This result sets new experimental constraints on recent theoretical studies on the formation and evolution of the Galactic disk(s).

### P56 - Tidal Stability of Interstellar Clouds in the Neighbourhood of Sgr A*Blake STAPLES, Macquarie University

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.

### P57 - A simple model for X-ray plateaux in short Gamma-Ray BurstsLucy STRANG, University of Melbourne

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.

### P58 - Computational Molecular Spectroscopy Towards New PhysicsAnna-Maree SYME, University of New South Wales

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.

### P59 - Stellar Populations and Star Formation of Clumps in Gas-Rich, Turbulent GalaxiesLiyualem Ambachew TILAHUN, Swinburne University of Technology

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.

### P60 - Winds from Protoplanetary DiscsJames TOCKNELL, Macquarie University

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.

### P61 - Molecules & Atoms from the Dark SideChenoa TREMBLAY, CSIRO

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.

### P62 - Viterbi methods and applications in gravitational wave analysisAndres Felipe VARGAS, University of Melbourne

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.

### P63 - K-CLASH: the spatial extent of star formation in field and cluster galaxies at 0.2<z<0.6Sam VAUGHAN, University of Sydney

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.

### P64 - Close double degenerate starsStephane VENNES, Australian National University

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.

### P65 - Robust quantification of asymmetries in global HI spectra as a function of galaxy propertiesAdam Brian WATTS, The University of Western Australia - International Centre for Radio Astronomy Research

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.

### P66 - Detecting Cosmic Rays using the MWAAlexander WILLIAMSON, Curtin Institute of Radio Astronomy

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.

### P67 - Broadband radio polarimetry of compact sources from QUOCKA surveyXiang ZHANG, CSIRO Astronomy & Space Science

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.

### P68 - ASKAP Detection of Periodic and Elliptically Polarised Radio Bursts from UV CetiAndrew ZIC, The University of Sydney

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.

### P69 - Wide-band Radio and Optical Space Weather Monitoring of the Proxima Centauri SystemAndrew ZIC, The University of Sydney

Stellar flares and coronal mass ejections (CMEs) play an important role in the habitability of their planetary companions. M-dwarf stars are particularly interesting in this regard, as they are known to flare much more frequently and powerfully than the Sun. At the same time, a large number of these stars are likely to host planets within their habitable zones. While stellar flares have been observed ubiquitously across the electromagnetic spectrum, observational identification and characterisation of space weather events such as CMEs around other stars is lacking. These space weather events are expected to cause effects such as magnetospheric compression and atmospheric stripping of planetary companions, degrading their habitability. One promising method to detect and characterise stellar CMEs is the detection of Type II radio bursts, generated at the CME shock front. The detection and characterisation of Type II bursts from other stars will lead to rich insights into their environment, and their impact on the habitability of planetary companions. In this poster, I will outline observations taken during an 11-night simultaneous multi-wavelength campaign targeting space weather events from Proxima Centauri. Involving the Parkes Radio Telescope, the Murchison Widefield Array, the Australia Telescope Compact Array, and the Australian Square Kilometre Array Pathfinder, this campaign represents one of the most comprehensive, wide-band radio-frequency campaigns of an active star to date. These radio-frequency observations were coordinated with optical observations with the Zadko Telescope, the ANU 2.3m Telescope, and NASA's TESS Satellite, to constrain the relationship between low-frequency radio bursts and optical flaring activity. I will present some early results from this work, and their possible implications for the space weather environment around Proxima Centauri.

### P70 - Model analysis done quickGerrit Willem VAN DER VELDEN, Centre for Astrophysics and Supercomputing, Swinburne University of Technology

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.

### P71 - Direct Detection of Messy HalosGrace LAWRENCE, Swinburne Centre for Astrophysics and Supercomputing

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.

### P72 - What you need to know to use the ExoMol line listLaura MCKEMMISH, University of New South Wales

ExoMol has made a name in producing high quality, complete high-temperature line lists for a wide variety of astrophysically relevant molecules, including biomarkers. These line lists (specifying the frequency and intensity of absorption lines in molecules) are used in complex atmospheric models to predict absorption based on temperature, pressure, atmospheric composition and other factors. But what if your observed spectrum doesn't match your model? Have you used the wrong input parameters? Is the atmospheric model wrong? Or is the underlying line list wrong? As a producer of line lists formally in the ExoMol group and now in Australia, I can help you answer the last question. I will tell you how we produce these line lists and, most importantly, where we expect errors to occur and where they will not occur (as well as tell you about what sort of errors and their magnitude). For example, if you are looking at water absorption around 3000 cm-1, then the line lists will be near perfect. Looking at VO at 17,000 cm-1 (in the visible) - not so much. Why? I will tell you what molecules, parameters and spectral regions are easy for us to study, and which are diffcult, and why this is the case. I will explain where experimental data is critical, the accuracy with which different input parameters can be calculated by ab initio theory, and how experiment and theory can be used together to build a more complete picture of the spectroscopy of molecules. And, if nothing else, you can learn why quantum chemists like me talk (and think) in cm-1.

### P73 - Group Environments have no Substantial Impact on the Circumgalactic Medium MetallicityStephanie Kate POINTON, Swinburne University of Australia

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.

### P74 - VLBI observations of radio starsOleg TITOV, Geoscience Australia

Radio stars are the celestial objects now observed by the astrometric facilities in radio (VLBI) and optics (Gaia). VLBI observations of the Galactic objects are important for calibration of the Gaia proper motions and parallaxes. A list of potential targets include stars of different spectral classes, planetary nebulae, HII zones, masers, etc. We discuss our plans for observing of radio stars with future VLBI networks.