2021 Seminar Archive
2021 MQAAAstro and MQ-AAO Seminars
Jaime Alvarado Montes - Macquarie University
12 February 2021
Title: The impact of tidal friction on the fate of ultra-compact planetary systems
Sabyasachi Goswami - International School for Advanced Studies, Italy (SISSA)
19 February 2021
Title: On the effects of Initial Mass function on the galactic chemical enrichment: the role of Pair Instability Supernovae
Sara Webb - Swinburne University of Technology
26 February 2021
Title: Flare Stars as seen with the Deeper, Wider, Faster Program
Dr Cormac Purcell - Trillium Technologies
12 March 2021
Title: Accelerated Research with NASA, ESA and the ASA
Dr Tim Carleton - Arizona State University
19 March 2021
Title: TBC
Dr Hadrien Devillepoix - Curtin University
26 March 2021
Title: Asteroids, fireballs, meteorites, and what they tell us about the early Solar System
Dr Felipe Jiménez Ibarra - Instituto de Astrofisica de Canarias
9 April 2021
Title: X-ray binaries: What optical spectroscopy can reveal about the brightest X-ray sources in the sky
Dr Jielai Zhang - Swinburne University of Technology
16 April 2021
Title: Simultaneous Multi-Wavelength Observations (Gamma, X-ray, UV, Optical, and Radio) of Two FRBs
Danny Horta Darrington - Liverpool John Moores University, UK
23 April 2021
Title: Unravelling the nature and origin of the Galactic stellar halo with Galactic surveys
Dr Katie Auchettl - University of Melbourne
30 April 2021
Title: The imprint of their explosions: Using supernova remnants to understand stellar death
Jonah Gannon - Swinburne University of Technology
7 May 2021
Title: The Dark Matter Content of Ultra-Diffuse Galaxies
Associate Professor Vicente Rodriguez-Gomez - National Autonomous University of Mexico
14 May 2021
Title: The optical morphologies of galaxies in the IllustrisTNG cosmological simulation
Riu Luo - CSIRO
21 May 2021
Title: Diverse polarization angle swings from a repeating fast radio burst source
Dr Haiyang Wang - ETH Zurich
28 May 2021
Title and Abstract: Comparative Planetology: From Stars to Planetary Atmospheres
Comparative Planetology is a terminology initially used for comparing our Earth to other solar system bodies to understand their similarities and differences. With the discovery of thousands of extrasolar planets (among them many are potentially terrestrial), this terminology has been increasingly popularised (with extended meanings) in exoplanetary science. In this seminar, I’ll discuss why and how understanding the star-planet chemical connections is crucial to conduct quantitative comparative planetology towards understanding the interiors, surface and atmospheres of terrestrial-type exoplanets.
Dr Zixin Huang - Macquarie University and Sydney Quantum Academy
3 June 2021
Title and Abstract: Sub-wavelength quantum imaging for astronomy
The resolution limit of standard imaging techniques is expressed by the Rayleigh criterion, which states that two point-like sources are difficult to resolve if their transverse separation is smaller than the Rayleigh length. While the criterion is useful in the case of direct detection imaging, other measurement techniques may not be subject to this limitation. Here we consider the use of imaging to estimate the distance between an arbitrary number of incoherent point sources. In the regime of weak signals, a structured measurement obtained by concatenating a linear interferometer with on-off photo-detection is immune to the Rayleigh curse. In this way, we clarify the relationship between imaging and interferometry, and establish the optimality of linear interferometry for an arbitrary number of incoherent sources.
Detecting the faint emission of a secondary source in the proximity of the much brighter stellar source has been the most severe obstacle for using direct imaging in searching for exoplanets.
Using quantum state discrimination and quantum imaging techniques, we show that one can significantly reduce the probability of error for detecting the presence of a weak secondary source, even when the two sources have small angular separations. If the planet has relative intensity $\epsilon \ll 1 $ to the star, we find that the error exponent can be improved by a factor of $1/\epsilon$; we also find the linear-optical measurement that is optimal in this regime. Our result serves as a complementary method in the toolbox for astronomy.
Shalmalee Kapse - Macquarie University
4 June 2021
Title and Abstract: Searching for multiple populations in young Magellanic Cloud star clusters
Observational studies of star clusters are important probes to understand stellar evolution theories and the star formation history of their host galaxies. Traditionally star clusters were believed to host single stellar populations, which implied that all the member stars of a particular cluster were assumed to be of similar age and chemical compositions. However, detection of star-to-star abundance spreads in light elements (e.g. C, N, O, Na, Mg, Al) in young (age ~ 1-3 Gyr) clusters using photometric and spectroscopic observations have completely revolutionized this past view. In the last decade, many young and intermediate-age (age ~ 3-6 Gyr) clusters have been found to host multiple stellar populations i.e. the member stars have a variety of ages and chemical compositions. I will talk about simple and multiple stellar populations residing in star clusters of our neighbouring galaxies, the Magellanic Clouds. In our recent work, we used photometric data from the Hubble Space Telescope to investigate the stellar evolutionary stages of such star clusters to understand their various properties such as helium and nitrogen abundance variations. Studies of these young star clusters in nearby galaxies will give us clues to the star formation history of our own galaxy, the Milky Way.
Dr Ryosuke Hirai - Monash University
11 June 2021
Title and Abstract: Energetic interactions with stellar companions
There are many forms of stellar explosions that are observed in the Universe, such as supernovae, kilonovae, X-ray bursts, stellar eruptions, etc. Many of these explosions originate from massive stars, which are predominantly members of binary or higher order multiple systems. Therefore the presence of companion stars may play a critical role in the mechanism of the explosion itself, or conversely, the explosion may affect the properties of the companion stars. In this talk, I will review our work on supernova explosions in binary systems, and stellar merger-driven eruptions in triple systems. I will show various examples where our numerical models reproduce the observed properties of some known explosions (e.g. supernova remnant Cassiopeia A, Great Eruption of Eta Carinae). I will also discuss how we can use the observations of stellar explosions to infer the evolution of the binary (or triple) system leading up to the explosion.
Professor Rachel Webster - University of Melbourne
18 June 2021
Title and Abstract: Detecting the Epoch of Reionisation: the Australian Project
Detection of the Epoch of Reionisation (EoR) is one of the major challenges in cosmology. Once achieved it is likely to herald a revolution in our understanding on a similar scale to the detection of the CMB inhomogeneities. In this talk I will provide a little background on the genesis of the Australian MWA experiment. I will explain the theoretical predictions for the EoR signal, and then present the most recent published limits. During this talk I will highlight some of the identified challenges that have been overcome, and finally suggest the next steps in this fascinating journey.
Dr Lee Spitler - Macquarie University
24 June 2021
Title and Abstract: The Huntsman Telescope: overview and some technical aspects of the facility
I will briefly describe Macquarie's Huntsman Telescope, an automated telescope consisting of 10 Canon lenses, which is now operational at Siding Spring Observatory. I will also focus on a few technical aspects of the facility: automated observations using an open-source python software, including managing 10 independent Camera units. If there is time, I will describe challenges related to a new "movie mode", which will obtain a ~200 frame per second movie of the transient sky.
Dr Bernhard Mueller - Monash University
25 June 2021
Title and Abstract: Explosions of Massive Stars - Exploring the Extremes
Most massive stars die in a spectacular core-collapse supernova explosion. These explosions are important foundries for many of the heavy elements in the universe, laboratories for matter under extreme conditions, and promising targets for multi-messenger astronomy. Normal supernovae with typical explosion energies, which are believed to be powered by neutrinos, are by now quite well understood theoretically despite some remaining questions. The most extreme explosions of massive stars, so-called hypernovae, have proved much more enigmatic. These are likely powered by some magnetohydrodynamic mechanism that taps the rotational energy of a rapidly spinning "millisecond magnetar" or a black hole accretion disk. I will present our current efforts to model the dynamics and key observables, such as nucleosynthesis yields, of explosions involving rapidly rotating neutron stars or black hole formation. I will also highlight that our understanding of the most extreme supernova explosions is inextricably linked to unsolved questions about rotation and magnetic fields in stellar evolution, some of which we can now start to address more directly with multi-dimensional MHD simulations.
Professor Joss Bland-Hawthorn - University of Sydney
1 July 2021
Title and Abstract: Large-scale waves crossing the Milky Way
Our Galaxy, the Milky Way, is a benchmark for understanding disk galaxies.
It is the only galaxy whose formation history can be studied using the full distribution of stars, from white dwarfs to supergiants. The oldest components provide unique insight into how galaxies form and evolve over billions of years. This is a veritable golden age for galactic archaeology with many large surveys now under way to map both chemistry and motions for stars in the Galaxy. Detailed 6D "phase space" information combined with chemistry for millions of stars heralds a new era in how we slice up the Galactic disc. This has already enabled the most remarkable discovery to emerge from ESA's Gaia satellite — the “phase spiral”. This phenomenon, which was not foreseen, is direct evidence of giant waves crossing the disc. We discuss how these Galactic waves are generated and what they tell us about our history.
We review the main science goals of galactic archaeology, and look to what the future may hold. These studies will continue to play a fundamental role far into the future because there are measurements that can only be made in the near field and much of contemporary astrophysics depends on such observations.
Aman Chokshi - University of Melbourne
2 July 2021
Title and Abstract: Satellite Measurements of MWA Beam Patterns
Understanding the beam shapes of the Murchison Widefield Array(MWA) tiles is particularly important to studies of faint structure such as extragalactic and polarised source mapping, and the Epoch of Reionization (EoR). In this talk I'll discuss a cheap experiment we designed and implemented to measure the beam shapes of 14 MWA tiles, in both polarizations and at multiple pointings, using communication satellites. Our measurements reveal the presence of significant inter-tile variations - asymmetric side lobe deformations as well as gradients in the ground screens - attributed to various local environmental effects. I'll also talk about how these measured beam maps are currently being incorporated into simulations of the EoR and extragalactic polarized emission to determine the best methods to improve instrumental calibration. Finally, I'll also demonstrate how other telescopes can implement similar experiments easily, using cheap off-the-shelf equipment.
Dr Mária Kieferová - University of Technology, Sydney
22 July 2021
Title and Abstract: Quantum computing: disentangling the hype
Quantum computing promises a revolution in computing by solving problems inaccessible to classical computers. While quantum computers can be potentially very powerful, the reality is much more nuanced. In this talk, I will discuss the current research in quantum applications development and explain the strengths and weaknesses of well-known quantum algorithms.
Adam Batten - Swinburne University of Technology
30 July 2021
Title and Abstract: The intergalactic medium through the lens of fast radio bursts and hydrodynamic simulations
The Intergalactic Medium (IGM) is a difficult observe in the optical and UV due to the high temperatures (T ~ 10^6K) and low densities (n ~ 10^-6 cm^-3) leading to a lack of favourable transition lines. The dispersion measure (DM) of fast radio bursts (FRBs) provides a unique new way to probe the ionized baryons in the IGM. Cosmological models with different parameters lead to different DM-redshift (DM−z) relations. Additionally, the over/under-dense regions in the IGM and intervening galaxies' circumgalactic medium lead to scattering around the mean DM−z relations. I will present the recent work I have done using the Evolution and Assembly of GaLaxies and their Environments (EAGLE) simulations to study the DM-z relation, and the scatter around it. I find that almost all of the FRBs found at low-redshifts have significantly larger observed DMs than predicted from simulations. I will also show that we would need of the order 9000 localised FRBs to constrain AGN feedback efficiency. Finally I will talk about a future project measuring the metallicity of the IGM in EAGLE and the sizes of ‘metal bubbles’ around galaxies at the end of the epoch of reionisation.
Lynn McDonald - Microsoft Azure Space Lead for Australia
12 August 2021
Title and Abstract: Microsoft Azure Space: Enabling Space Technologies Through Hyperscale Cloud
Microsoft is using the power of cloud computing and connectivity to enable the Space industry and customers of space technologies. Azure Space is integrating Azure cloud with an ecosystem of space partners to develop multi-orbit, multi-band, multi-vendor capabilities. Azure Space is focused on bringing together innovation and partnerships to help the industry and our customers do more on and off the planet.
Dr Penny Crook and Professor Shawn Ross - Macquarie University
19 August 2021
Title and Abstract: The FAIMS Mobile Platform
The FAIMS Mobile Platform (Field Acquired Information Management Systems) is open-source software for offline data collection on an Android device. It was established by archaeologists in 2012 to support the capture and management of digital field data in remote locations. It is now used by researchers from many fields in diverse situations but the software is showing its age. In 2020 we received a major investment from the ARDC and project partners to rebuild from the ground up. AAO is leading the development of FAIMS 3.0 to enable cross-platform data collection (Android, iOS and desktop), more flexible synchronisation, integration with Cloudstor, a DIY option for customisation, and a sleek new look. In this talk we discuss the use cases of FAIMS over the past 9 years and our plans for future adoption and adaptation.
Anita Petzler - Macquarie University
20 August 2021
Title and Abstract: Hydroxyl as a probe of the molecular interstellar medium
The molecular gas of the interstellar medium plays a key role in the gas cycle of a galaxy, but its main component -- molecular hydrogen -- is all but invisible in the cold environments in which it is expected to be found. Instead we must rely on other molecular tracers -- such as hydroxyl -- to detect this molecular gas and measure its properties. In this talk I'll discuss the work I've done in my PhD, which is to explore the versatility of hydroxyl as a tracer of the molecular interstellar medium. This work includes the development of 'Amoeba', a fully automated algorithm that uses Bayesian model comparison to tackle the problem of the Gaussian decomposition of hydroxyl spectra. My work also includes the discovery of the physical mechanism responsible for the hydroxyl satellite-line 'flip': a strange pattern seen in the spectra of two of hydroxyl's transitions that had remained a mystery for decades.