Monday, 3rd of July

Detailed programme for Monday, 3rd of July. 

All times listed in AEST. Click on the arrows to expand each session. 

speaker presenting remotely    * student talk

10:00am - 11:00am: Registration (from 10am) & Morning Tea (from 10:30am) 

11:00am - 12:15am: Session 1 - Welcome + Ellery lecture (plenary)

Location: Mason theatre, ground floor

Zoom link:

Slack channel: #asm-plenary

Chair: Richard McDermid,  Co-Chair: Elizabeth Mahony

11:00am Welcome + Housekeeping

11:15am: Ellery Lecture: Dark Energy and Cosmological Tensions -Tamara Davis, UQ

The last few decades have been a golden age for observational astrophysics and cosmology, thanks to the power of modern telescopes.  From unveiling properties of dark matter and dark energy, to measuring the mass of the neutrino, and exploring the blossoming field of gravitational waves, modern astrophysics is now a key tool in studying fundamental physics.  In this Ellery Lecture Tamara Davis will summarise the main methods by which astrophysicists are pushing the boundaries of known physics — including some case studies of her work with the Dark Energy Survey — and discuss whether the cracks (“tensions”) that are emerging between different cosmological probes could indicate the need for new physics. 


Professor Tamara Davis is an astrophysicist and ARC Laureate Fellow at the University of Queensland with over two decades experience studying supernovae, black holes, and dark energy. She led the Dark Theme in the Australian Centre of Excellence for All-sky Astrophysics, is currently leading the Australian Dark Energy Survey (OzDES), and was recently announced as the Deputy Director of the upcoming renewal of the Centre of Excellence for Gravitational Wave Discovery. She previously won the Astronomical Society of Australia’s Louise Webster prize for early career achievement, and her other accolades include the Australian Academy of Science’s Nancy Millis medal for female scientific leadership, and an Order of Australia (AM).”

She is an avid communicator of science and occasional guest host of ABC TV’s “Catalyst”, including the episode “Black Hole Hunters” which won the American Institute of Physics Science Communication Award.  When not doing science she loves playing sport — she’s competed at a representative level in seven sports, from surf life saving to gymnastics, and has captained Australia in the (albeit obscure) sport of Ultimate Frisbee.

12:15pm - 1:15pm: Break / ECR chapter meeting

Sponsored by ICRAR

Chapter meeting location : Mason Theatre, ground floor

Zoom link:

Slack channel: #chapter-ecr-community

Chair: Henry Zovaro

1:15pm - 2:15pm: Session 2a - Galaxies: radio surveys

Location: Mason theatre, ground floor

Zoom link:

Slack channel: #asa2023-galaxies

Chair: Julia Bryant, Co-Chair: Anais Möller

1:15pm: A very efficient survey to study sub-arcsecond scale objects at low radio frequencies  - Rajan Chhetri, Curtin University

Understanding sub-arcsecond scale radio source population is important to understand the radio galaxy source population. This is particularly difficult at low frequencies, where the challenge of angular resolution has prevented large scale studies of this population. We developed the technique of widefield interplanetary scintillation (IPS) with the Murchison Widefield Array (MWA) that very efficiently identifies compact objects in large numbers (at 162 MHz ~10% of ~3000 objects detected in a single 10 minute observation are compact). We found that the compact source population at low frequencies is quite different compared to its gigahertz counterpart. The blazars population dominant at gigahertz frequencies gives way to peaked spectrum sources as the dominant population at low frequencies. I will present these results, and outline current developments of the technique with the ASKAP telescope which provides an important way to study space weather. I will show that the technique increases the capability of both the ASKAP and SKA-low to probe objects at over an order of magnitude larger range of angular scales, and will provide a high density of calibrators necessary for the multi-facet calibration required for the SKA.

1:30pm: The Evolutionary Map of the Universe - Andrew Hopkins, Macquarie University/WSU

EMU, the Evolutionary Map of the Universe, is an ongoing ASKAP survey of the southern hemisphere, delivering 943 MHz continuum images with rms noise 20 microJy/beam at 15 arcsec resolution. EMU will support a broad range of science, spanning star formation and evolution in our own Galaxy, galaxy evolution and the links between star formation and supermassive black holes, to cosmology. EMU will be the touchstone radio continuum survey in the south for the foreseeable future. I will summarise the scientific goals of EMU, the current status of and timeline for the survey, highlight a selection of recent results, and describe how to get involved in the project.

1:30pm: First results from ASKAP POSSUM - Polarisation Sky Survey of the Universe’s Magnetism - George Heald, CSIRO

POSSUM, the Polarisation Sky Survey of the Universe’s Magnetism, will use ASKAP’s unique survey capabilities to transform our understanding of astrophysical magnetic fields. Commensal with both the EMU and WALLABY surveys, POSSUM will utilise sensitive spectopolarimetric data to generate a dense and precise grid of about a million background Faraday rotation measures that probe foreground objects. POSSUM aims to revolutionise our understanding of magnetic fields and their role in fundamental physical processes across a wide range of scales: in the interstellar medium; the large-scale Milky Way and halo; external galaxies dominated by star formation, active galactic nuclei or merger activity; galaxy clusters; the cosmic web; and the intergalactic medium. At a deeper level, POSSUM seeks to reveal how the first magnetic fields were generated, and to understand the processes that organised and strengthened those fields to the present day.

The POSSUM collaboration has worked for years to develop new techniques to produce, analyse, and distribute polarisation data. We have also worked closely with ASKAP to understand the polarimetric performance of the telescope and improve the required calibration and imaging. In this talk I will briefly summarise the science aims of the POSSUM project, and then highlight results from two iterations of POSSUM pilot surveys, and the first observations of the recently commenced full 5-year POSSUM survey program.

2:00pm: Progress with WALLABY - Lister Staveley-Smith, CSIRO, Curtin University

Full WALLABY survey observations have now started on ASKAP, with the goal being to map at least half of the southern sky in HI to a redshift depth of z=0.1. I will summarise some of the first results from full WALLABY. This includes extensive insights into the interplay of ram pressure and tidal forces in the outskirts of large groups and dynamically young clusters, and the implications for galaxy transformation and evolution. I will also discuss synergies with other current and planned large-area multi-wavelength Australian-led surveys using 4MOST, AAT, ALMA as well as future implications for LSST and MeerKAT/SKA science directions. Combined with theoretical models, the coming decade is likely to see an improved understanding of the baryon cycle in galaxies and new constraints on the physics of gas accretion, cooling and galactic outflows. 

2:15pm: Results from the FLASH Pilot Surveys: ASKAP HI 21-cm absorption observations toward 0.42 < z < 1.00 - Hyein Yoon, University of Sydney

Detections of HI in absorption towards distant radio galaxies can provide a powerful tool in understanding the role that cold gas plays in the formation and evolution of galaxies. We present the results of pilot surveys for the First Large Absorption Survey in HI (FLASH), which were successfully carried out from 2019 to 2022. FLASH is a large-area neutral hydrogen (HI) absorption line survey using the Australian Square Kilometre Array Pathfinder (ASKAP) to search for the HI 21-cm line in the redshift range 0.42 - 1.0. By detecting HI in absorption we can probe the neutral hydrogen gas in and around galaxies over the past 7-8 Gyr of cosmic time, an epoch where the gas content of galaxies is poorly constrained.

In this talk we present results from the FLASH pilot survey observations which covered ~3,000 sq. degrees in 200 hrs of observing time. We will highlight several new detections from both associated systems, where the HI gas is at the same redshift as the background radio source, and intervening systems where the HI gas is in the foreground along the line-of-sight. These results also provide an initial insight into the detection rate and typical properties of HI absorption systems that we could expect from the full FLASH survey; a wide-field radio survey with no optical pre-selection.

2:30pm: An ‘Almost’ Dark Cloud in the Compact Interacting Group Klemola 13 - Tamsyn O'Beirne*, ICRAR-UWA/ASTRO-3D

Dark galaxies are isolated, dark matter dominated systems without optical counterparts that are predicted by LCDM simulations, yet observations have shown them to be rare. In our search for dark galaxies using the pilot data of the Widefield ASKAP L-band Legacy All-sky Survey (WALLABY), six candidates were found, one of which had archival data available which confirms its reality. We show that this source is not isolated, but part of an interacting group known as Klemola 13. Unlike the previous studies, we’ve identified a faint optical counterpart, leading us to call this source an 'almost' dark cloud. By combining the WALLABY data with the archival data, we’ve studied the HI distribution and kinematics of the almost dark cloud and the compact group it resides in. We conclude that the almost dark cloud is a tidal remnant resulting from interactions within the group. It appears to have enough mass to become a tidal dwarf galaxy (TDG). Being situated close to the virial radius of the Hydra cluster, the future evolution of the TDG will be strongly influenced by ram pressure stripping. The detection of this almost dark HI cloud showcases the potential of the full WALLABY survey to detect this class of objects, despite their rarity. 

Poster sparklers in this session:

P21: Kathryn Ross, ICRAR/Curtin Uni.  

P33: Sarah Bradbury*, ANU

P36: Nikhel Gupta, CSIRO

P72: Tania Ahmed*, Macquarie Uni.

1:15pm - 2:15pm: Session 2b - Planets I

Location: T2, second floor

Zoom link:

Slack channel: #asa2023-planets

Chair: Laura Driessen, Co-Chair: Daniel Zucker

1:15pm: Spectroscopic Data for Molecule Identification in Exoplanets and Cool Stars - Laura McKemmish, University of New South Wales

New telescopes (particularly JWST) and observational techniques (notably high-resolution cross-correlation, HRCC) offer tantalizing opportunities for astronomers to study in unprecedented detail the chemical composition of a variety of exoplanet atmospheres. However, these studies are only possible if sufficiently high-quality spectroscopic data is available for the molecules of interest.

Modern methods for producing molecular spectroscopic data are advanced and can, for the right molecules and spectral regions, address the dual challenges of accuracy and completeness. They accomplish this by careful use of both experimental and theoretical data.

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, 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 in the infrared, then the line lists will be near perfect. Looking at TiO in the visible, not so much. 

1:30pm: Transit Depth Variations Reveal TOI-216 b to be a Super-Puff - Brendan McKee*, University of New South Wales

Transit timing variations are a powerful tool in exoplanet characterisation, allowing planetary masses to be determined using transits alone. In orbital resonances perturbations add constructively to push transits earlier or later than expected from a strict periodicity. Only a small number of systems have transit timing variations large enough to determine the masses of the planets using transits alone, without seeking further data from radial velocity measurements. The planets of TOI-216 exhibit the most extreme periodic timing variations known, with deviations of up to 3 days from the expected arrival time out of its 17-day orbit. Using new observations, we find that the depth of the transit of TOI-216 b also changes over time as interplanetary forces cause the planet to cross more of the face of the star. This rare feature allows us to precisely characterise the orbital architecture, along with both the masses and radii of each planet. We find that this system has a typical gas giant as the outer planet, while the inner planet has the same mass as Neptune, despite having 8 times the volume. While the origins of super-puff planets are unclear, TOI-216 b represents a growing class of these objects in orbital resonances and with a companion in a nearly circular orbit, suggesting their early evolution is driven by smooth disk migration.

1:45pm: Direct Imaging of Protoplanet HD 169142 b - Iain Hammond*, Monash University

We present the re-detection of a compact source in the face-on protoplanetary disc surrounding HD 169142, using VLT/SPHERE data in YJH bands. The source is found at a separation of ∼37 au from the star. Three lines of evidence argue in favour of the signal tracing a protoplanet: (i) it is found in the annular gap separating the two bright rings of the disc, as predicted by theory; (ii) it is moving at the expected Keplerian velocity for an object at ∼37 au in the 2015, 2017, and 2019 data sets; and (iii) we also detect a spiral-shaped signal whose morphology is consistent with the expected outer spiral wake triggered by a planet in the gap, based on dedicated hydrodynamical simulations of the system. The YJH colours we extracted for the object are consistent with tracing scattered starlight, suggesting that the protoplanet is enshrouded in a significant amount of dust, as expected for a circumplanetary disc or envelope surrounding a gap-clearing Jovian-mass protoplanet.

2:00pm: Do you want to detect a non-transiting exoplanet? Then you should put a ring on it. - Jaime Andres Alvarado Montes*, Macquarie University

The two most accomplished techniques for exoplanet detection are transits and radial velocity (RV). However, these methods have a bias towards close-in, low-inclination orbits, which means that certain orbital configurations are not detectable. Here, we aim to develop a robust photometric model to study the complete phase curve of gas giants with rings, since spatially unresolved dusty rings can modify the total flux of reflected starlight. We base our radiative transfer calculations on an adding-doubling algorithm and compute the reflected flux, linearly polarized flux, and degree of polarization curves, varying properties such as the ring orientation, size, particle albedo, optical thickness, and the planet orbital inclination. Additionally, we populate rings with irregularly shaped particles with optical properties based on measurements. Our findings show that dusty rings produce sharp discontinuities in the degree of polarization curves at the planet's apoastron and periastron. We also predict the reflected and polarized flux of the "puffed-up" planet HIP 41378f, proving that while it cannot yet be directly imaged, polarimetry in future observations will significantly aid in characterising ringed exoplanets. By investigating the reflected flux and polarization curves of planets, we can cover orbits that are undetectable using transits and RVs, thus increasing the probability of discovering new extrasolar systems that may be invisible to existing techniques.

2:15pm: Exploring spin-orbit alignment of exoplanet and binary star systems - Tony Wells*, University of Southern Queensland

Until the discovery of exoplanets, theories on planet formation and orbital evolution were based on observations of the one known planetary system – the Solar System. Recent observations of exoplanet and binary star systems however have revealed planets and stellar companions in orbits wildly different from those observed in the Solar System, including bodies in polar and even retrograde orbits. Such observations have raised difficult questions as to the nature of the processes that drive the planets/stars to these remarkable orbits. One powerful indicator of the dynamical history of a planetary system is the stellar obliquity, (or spin-orbit angle), which describes the angle between the stellar rotational axis and the planetary (or stellar companion) orbital axis. Unfortunately, obliquity studies to date have been limited to a small number of system types. In this study we aim to expand this data base by determining obliquities for lesser studied system types including those featuring smaller planets and those on longer orbits, as well as binary star and brown dwarf systems. In this way we will create a more universal test bed of data with which to better understand the migratory processes driving the evolution of exoplanet and binary star systems. In this presentation I will discuss various formation and migratory scenarios, outline the study methodology, and present some preliminary findings. 

2:30pm: Hunting cold planets: Breaking the low mass planet detection limit with Euclid and Roman - Efstathia Natalia Rektsini*, University of Tasmania

The ESA EUCLID mission and NASA Nancy Grace Roman Space telescope mission have the potential to detect thousands of planets across a broad range of masses and semi-major axes. The ROMAN telescope will utilize the gravitational microlensing technique which is a unique tool for detecting and studying cold exoplanets of masses in the range Mars to Jupiter, orbiting any kind of star or stellar remnant all the way to the Galactic Bulge.

Gravitational microlensing relies on the chance alignment of two or more stars in our galaxy. Over 100 planets have so far been found using this technique, and the Roman Telescope is expected to increase that by a factor of ten. Both ROMAN and EUCLID will be located in halo orbits at the Earth-Sun L2 point, with a potential separation between them of up to 600.000 km, while observing the same sky frame.

Using simulated early EUCLID images of a star field containing 1691 microlensing events that ROMAN will observe, I will explain the complementarity of the two missions. I will show how two joint-surveys will better constrain the mass and distance of microlensing events, increase the detection of “free-floating” planets (FFPs) and lead to a breakthrough in our understanding of cold planet demographics and planetary formation theories.

Poster sparklers in this session:

P21: Kathryn Ross, ICRAR/Curtin Uni.  

P33: Sarah Bradbury*, ANU

P36: Nikhel Gupta, CSIRO

P72: Tania Ahmed*, Macquarie Uni.

2:45pm - 3:15pm: Break

3:15pm - 4:15pm: Session 3a - Galaxies: optical surveys

Location: Mason theatre, ground floor

Zoom link:

Slack channel: #asa2023-galaxies

Chair: Joanne Dawson, Co-Chair: Ángel Lopez-Sánchez

3:15pm: The Deep Extragalactic VIsible Legacy Survey - Luke Davies, University of Western Australia/ICRAR

The Deep Extragalactic VIsible Legacy Survey (DEVILS, Davies 2018) is a recently completed large spectroscopic survey on the Anglo-Australian Telescope (AAT), producing a deep (Y-mag<21) and high completeness (>90%) sample for studying galaxy and structural evolution. The spectroscopic sample is combined with extensive multi-wavelength imaging (Davies 2020) and the application of state-of-the-art analysis techniques to derive robust galaxy properties out to z~1. Importantly this analysis is undertaken in an identical manner to the Galaxy And Mass Assembly (GAMA) survey, forming a complementary high redshift sample and allowing a consistent analysis of galaxy properties from z~1 to today.

Here we present a summary of early science results exploring the evolution of stellar mass and star-formation (Thorne 2021, Davies 2022, Cook 2023a, D’Silva 2023), metallicity (Thorne 2022b), AGN (Thorne 2022a), and galaxy structure/morphology (Hashemizadeh 2021, Cook 2023b), providing a comprehensive study of evolution of galaxies over the last 8Gyrs. We also detail the first DEVILS data release that will contain all spectra, imaging, SEDs and structural analysis in the D10 (COSMOS) region, being released via Data Central later this year. 

3:30pm: Connecting age, environment and mass to galaxy kinematics with SAMI - Identifying the drivers of morphological transitions - Scott Croom, University of Sydney

The SAMI Galaxy Survey 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 kinematic and morphological transformations.

Galaxies in high-density environments have lower spin (i.e. lambda_r), but what is it about the environment that generates this kinematic difference? Similarly, passive galaxies have lower spin than star forming galaxies of the same mass. Is this related to environment? To tackle these questions we look at the correlation between spin, stellar mass, age and environment.

The striking result of our analysis is that the strongest correlation with spin comes from stellar age. Once age and mass are accounted for, there is little or no residual correlation with environment. The implication is that environment drives quenching and then quenching modulates galaxy spin. The environment does not directly impact spin. This rules out environmentally related dynamical processes for modulating spin. Instead, spin must change either through internal processes, not related to environment, or be influenced by progenitor bias.

3:45pm: Unifying observations and theory: Investigating radial trends in star formation across cosmic time with the MAGPI survey  - Marcie Mun*, Australian National University

Integral field spectroscopy has allowed astronomers to probe the local variations of properties within galaxies revealing the physical processes governing their local and global star formation activity. Large galaxy surveys (e.g., MaNGA), as well as simulations (e.g., IllustrisTNG), have revealed radial trends in star formation with respect to the star-forming main sequence (SFMS). However, unifying observational and theoretical results is challenging. Utilizing adaptive optics with MUSE, the MAGPI survey allows us to extend results in the local universe, to a crucial time of 4 Gyr ago when simulations predict the greatest diversity in evolutionary pathways for central and satellite galaxies. Furthermore, MAGPI aims to bridge the gap between observations and simulations by creating MUSE-matched mock data cubes from a suite of simulations as a means of direct comparison. I will present radial profiles of star formation activity as a function of location with respect to the SFMS at z ~ 0.3 (including star-forming and ‘passive’ galaxies), to understand the physical processes at work. I will then tie the results to the local universe and preliminary results with mock data cubes from simulations, which include EAGLE and HorizonAGN.

4:00pm: The Hector Galaxy Survey - the AAT's new large integral-field spectroscopic dark-time survey - Julia Bryant, University of Sydney

Hector is a new optical integral field spectroscopic (IFS) instrument that has recently been commissioned on the Anglo-Australian Telescope (AAT). It is now beginning a 15,000-galaxy IFS survey of nearby z<0.1 galaxies. New high fill-factor imaging fibre bundles `hexabundles’ cover up to 27-arcsec diameter across each galaxy. A new spectrograph has the highest spectral resolution of any large IFS nearby galaxy survey. This is key to enable higher order stellar and gas kinematics to be measured on a larger fraction of galaxies and to link those galaxies to the large-scale environments in which they form. The wider hexabundles plus the ability to resolve emission line doublets and apply multi-component fits to lines will enable gas feeding and feedback to be traced through winds and outflows.

Overlapping 4MOST WAVES regions data will give the environment metrics necessary to relate how local and global environments influence galaxy growth through gas accretion, star formation and spins measured with Hector. The WALLABY ASKAP survey will trace HI gas across the Hector fields, to give a complete view of gas accretion and star formation.An overview of the Hector Survey and first light results will be presented.

Poster sparklers in this session:

P20: Amir Ebadati Bazkiaei*, Macquarie Uni.

P26: Nicolò Dalmasso, Uni. Melbourne, ASTRO-3D

P29: Philip Lah, ANU

3:15pm - 4:15pm: Session 3b - Planets II

Location: T2, second floor

Zoom link:

Slack channel: #asa2023-planets

Chair: Manisha Caleb, Co-Chair: Andrew Hopkins

3:15pm: A Comparison of the Rotation Periods of Single and Binary Planet-Hosting and Non-Planet Hosting Stars - Tania Ahmed*, Macquarie University/University of Southern Queensland

We present an analysis of the rotation periods of stars in four categories: single stars with and without giant planets and binary stars with and without giant planets. This work seeks to assess the evolutionary influence on the presence of stellar companions and planetary companions on the formation evolution of planetary systems. Built on a sample of nearly 300 FGK stars that were systematically surveyed for both stellar companions and giant planets, our work uses TESS light curves to determine the rotation periods of stars in an effort to address how the presence of stellar and/or planetary companions can affect the angular momentum distribution within the systems. The comparison will be used to search for and characterize similarities and differences that may provide clues to the understanding of planetary formation and evolution in single and multiple star systems. We will focus on comparing the rotation periods of single stars known to host planets and not known to host planets to those of multiple stars known to host planets and not known to host planets. In particular, the angular momentum distribution of stellar systems (as measured by rotation periods of stars and orbital motion of the planets, if present) may be substantially different in planet-hosting stars as compared to non-planet hosting stars – or in comparison to multiple stars with or without planets.

3:30pm: Unveiling a Rare Pair of Super-Neptunes with TESS and CHEOPS - Tyler Fairnington*, University of Southern Queensland

Super-Neptunes — planets slightly larger than Neptune — are an intrinsically rare population of planets unlike any found in the Solar System. How did these planets form, are they similar to the ice giants in our own Solar system, or are they hydrogen-helium rich worlds that formed close-in to their parent stars?

We have a program on ESA's CHEOPS space telescope and NASA's TESS mission to discover and characterise these rare planets. From this program, we report the discovery of TOI-5126, a system of two super-Neptunes around a bright F star. Of particular note, the inner planet lies in a regime that is heavily bombarded by the intense stellar irradiation, and may be undergoing active atmospheric evaporation. Additionally, the planets are positioned on either side of the predicted cloud-free atmosphere threshold, opening the avenue for a comparative atmospheric planetology study, the first of its kind for a pair of super-Neptunes. We also report tentative detections of Transit Timing Variations -- gravitational interactions between the two planets -- that may help us measure the mass of these small planets. Such measurements are critical to understanding their atmospheric evolution, and are impossible to achieve via traditional radial velocity observations.

3:45pm: The occurrence rates of young, Neptune-sized planets with ages less than 100 Myr  - Sydney Vach*, University of Southern Queensland

Within the first 100 Myr, planetary systems undergo many evolutionary processes which shape their physical properties. The intense XUV irradiation from young, active host stars is thought to strip planets’ primordial atmospheres. The only means to holistically probe this violent, yet universal process, is to compare the population of planets around young stars against that of their mature counterparts. As an all-sky survey, NASA's Transiting Exoplanet Survey Satellite (TESS) is able to detect some of the earliest planetary systems, providing glimpses into these various stages of planetary evolution. In this talk, we will present a first glimpse of the occurrence rates of short-period, young planets (<100 Myr), as detected in both the short and long cadence TESS observations. Further, we present our planet detection pipeline, surveyed population, and our search procedure. We look to extend the criteria of our search to provide a comprehensive look into the relationship between ages and the properties of planets. 

4:00pm: Quantum meets astrobiology: Approximate vibrational spectral data for potential biosignatures - Maria Pettyjohn* (on behalf of Juan Camilo Zapata Trujillo), University of New South Wales

The scientific search for extraterrestrial life relies on the atmospheric detection of molecules that could be related to biology on a given (exo)planet (biosignatures). Such atmospheric detections require high-resolution spectral data, which is relatively sparse and only available for a limited number of molecules, restricting the scope of molecular detections in (exo)planetary atmospheres.

We constructed a new dataset storing approximate infrared spectral data for thousands of potential biosignatures using a reliable automated pipeline of quantum chemistry calculations. Though not accurate enough to enable definitive molecular detections in (exo)planetary atmospheres, we have showcased the benefits of this big data in screening potential molecular candidates responsible for unknown spectral signals. Specifically, we have listed molecular species that could be responsible for the unknown spectral peak at 4.56um present in the IR spectrum of WASP-39b. Further applications of this big data also include sorting strong molecular absorbers and recognising potential molecular ambiguities in spectra.

The emerging data from the James Webb Space Telescope is providing extraordinary opportunities for a new understanding of the chemistry of (exo)planetary atmospheres. Our quantum-chemistry big data will play a crucial role in supporting this understanding by giving directions into possible initial identifications of the more unusual molecules to emerge.

Poster sparklers in this session:

P20: Amir Ebadati Bazkiaei*, Macquarie Uni.

P26: Nicolò Dalmasso, Uni. Melbourne, ASTRO-3D

P29: Philip Lah, ANU

4:15pm - 5:30pm: Session 4 - ASA prize talks I (plenary)

Location: Mason theatre, ground floor

Zoom link:

Slack channel: #asm-plenary

Chair: Stas Shabala, Co-Chair: Tayyaba Zafar

4:15pm: Anne Green Prize talk: Levelling up the Southern Hemisphere: Breathing new life into VISTA and WISE - Michelle Cluver, Swinburne 

As the Southern sky prepares for a significant glow-up with the SKA, LSST, Euclid, HECTOR and 4MOST (among others) coming online, WISE is approaching 15 years since its launch into Earth orbit. But, instead of fading into oblivion (I'm looking at you, JWST) the WISE all-sky survey is coming into its own thanks to many years of dedicated effort, by researchers across the globe, into characterising and investigating how best to make use of this “infrared vision” we have across the entire sky. And when the 4MOST Hemisphere Survey (4HS) begins its 5-year, 6 million redshift mission at the end of 2024, we will be ready to incorporate the central measures of stellar mass and star formation activity. However, building this into a cohesive, if not fundamental, understanding of the baryon cycle, star formation histories and the role of environment will require the combined efforts of an entire community. And the one single thing we all have in common...

4:40pm: Bart Bok Prize talk: Dissociation of gas and dark matter in cosmic large-scale structure - William McDonald, UWA/Leiden Observatory 

The partial spatial separation of cold dark matter (DM) and gas is a ubiquitous feature in the formation of cosmic large-scale structure (LSS). This separation, termed dissociation, is prominent in galaxy clusters that formed through collisions of massive progenitors, such as the famous 'Bullet' cluster. A direct comparison of the incidence of such dissociated structures with theoretical predictions is challenged by the rarity of strongly dissociated systems and the difficulty to quantify dissociation. 

We introduce a well-defined dimension-less dissociation index, S, that encodes the quadrupole difference between DM and gas in a custom region. Using a simulation of cosmic LSS with cold DM and ideal non-radiative gas in Lambda-CDM cosmology we find 90 per cent of the haloes are positively dissociated, implying their DM is more elongated relative to the gas. Furthermore, we find that the volume density of highly dissociated massive structures appears consistent with observations. 

Through a suite of 300 idealised N-body+SPH simulations of colliding gaseous DM haloes, we explore the relationship between dissociation in binary collisions. Revealing a scale-free relation between the orbital parameters of binary collisions and the resulting dissociation. Building on this relation we conclude that the frequency of dissociated structures in non-radiative cosmological simulations is well accounted for by the major binary collisions predicted by such simulations. In principle, our results allow us to constrain the orbital parameters that produced observed dissociated clusters.

The possibility of using turbulence induced by dissociative collisions as an indicator of the recent merger history was examined by the development of custom numerical tools. 

5:00pm: Charlene Heisler Prize talk: When did the IMF become bottom-heavy? - Piyush Sharda, ANU/Leiden Observatory 

The peak of the stellar initial mass function (IMF) characterises whether it is top- or bottom-heavy, and plays a fundamental role in virtually all of galaxy evolution. Star formation theories find that the IMF peak is closely linked to the thermodynamics of interstellar gas, which controls how gas fragments as it collapses under gravity. As the Universe has grown in metal abundance over cosmic time, this thermodynamic behaviour has evolved from a primordial regime dominated by molecular hydrogen cooling to a modern regime where the dominant process in dense gas is protostellar radiation feedback, transmitted to the gas via dust grains. In this talk, I will present a new set of models we develop to study gas thermodynamics in collapsing dusty molecular clouds at a wide range of metallicities, from primordial to super-Solar, in different ISM conditions. We show that the transition in the IMF from the primordial regime to the modern regime begins at metallicity Z 0.0001*Z, passes through an intermediate stage where metal line cooling is dominant, and then transitions to the modern dust- and feedback-dominated regime at Z 0.05*Z. This transition is accompanied by a dramatic change in the characteristic stellar mass, from 50 Msun at Z 10^(−6) Z to 0.3 Msun once radiation feedback begins to dominate, which marks the appearance of the bottom-heavy Milky Way IMF. The exact transition from top- to bottom-heavy IMF occurs at intermediate metallicities. This transition is also sensitive to the abundances of C and O, which observations of metal-poor stars in the Milky Way and H II regions in dwarf galaxies find to be non-Solar-scaled. Our models will be directly tested by upcoming JWST programs aimed at measuring IMF variations in diverse environments. This testing has the potential to redefine our understanding of galaxy evolution in the early and metal-poor Universe.

5:30pm - 8:30pm: Welcome reception 

Ubar, Macquarie University

5:30pm - 7:30pm: ADACS training workshop: Introduction to Machine Learning 

Intro to Machine Learning (online only)

Facilitator: Paul Hancock 

Zoom link:

This lecture-style session will focus on what is ML/AI, where it's been used successfully, some common pit-falls, and what people can expect in terms of time/effort investment and outcomes.