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Colloquia Series

For more information on colloquia at the Centre for Astrophysics and Supercomputing please contact Dr. Joel Pfeffer or Dr. Barbara Mazzilli Ciraulo ()

Swinburne Virtual Reality Theatre
AR Building, Room 104
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2020 Colloquia

Tuesday Dec 15, 10:30
Mitchell Dixon CoC ()
Student Review: H0 tension
Thursday Dec 10, 10:30
Arika Egan (Colorado University)
Colloquium: The Colorado Ultraviolet Transit Experiment (CUTE) mission
The past few years of space mission development has seen an increase in the use of small satellites as platforms for dedicated astrophysical research. Small satellites offer unique and complimentary advantages over large shared resource facilities like the Hubble Space Telescope, including: low cost and relatively low risk, quick development timelines, observing strategies often dedicated to niche but important science questions, and ample opportunity for students and early career scientists and engineers to be involved on the front lines of space mission development. One such satellite is the Colorado Ultraviolet Transit Experiment (CUTE), a 6U CubeSat dedicated to observing the evolving atmospheres on short-period exoplanets. Supported by NASA and undergoing integration and testing at the Laboratory for Atmospheric and Space Physics, CUTE is planned for launch in 2021 and will provide moderate-resolution near-ultraviolet transit spectroscopy of approximately one dozen short-period exoplanets. The data will reveal crucial information regarding the shape, size, and composition of exoplanet atmospheres, contributing to our understanding of planetary formation and evolution. Additionally, CUTE has enabled several early-career scientists and engineers, ranging from undergraduates to recent PhDs, to work directly on an astrophysics space flight mission. This talk will cover all aspects of the CUTE mission, including the mission operation, opportunities for student involvement, and the exciting and essential science the mission will contribute to exoplanet studies.
Tuesday Dec 8, 10:30
Adam Batten (CAS)
Student Review: Adam Batten DTR
Thursday Dec 3, 10:30
Amol Upadhye (UNSW)
Colloquium: Neutrinos and cosmic clustering
Cosmological measurement of the absolute neutrino mass scale, one of the final unknown parameters of the Standard Model of particle physics, is within sight. Beyond that lie more detailed observations of the impact of neutrinos on structure formation, which in turn demand more accurate theoretical calculations of the clustering of matter. I discuss three aspects of clustering in massive neutrino cosmology, beginning with recent constraints using a galaxy redshift survey. Next I study the clustering of neutrinos themselves and the extent to which it is enhanced by the non-linear clustering of cold matter. Finally, I consider the ratio of power spectra with different neutrino masses and trace its characteristic features to the formation of dark matter halos.
Tuesday Dec 1, 09:30
Jonah Gannon (CAS)
Student Review: Mid Term Review for Jonah Gannon
Mid Term Review for Jonah Gannon
Password 527718
Thursday Nov 26, 10:30
Simon Stevenson (Swinburne University of Technology)
Colloquium: Gravitational wave discoveries from LIGO/Virgo in 2019/2020
Gravitational waves have been providing an entirely new way to study the Universe since their discovery in 2015. In this talk, I will present an overview of recent results from data taken by the Advanced LIGO and Virgo gravitational wave detectors in 2019/2020. These observations bring the total number of gravitational waves observed to over 70. Highlights include the observation of a second binary neutron star merger, two binaries with highly asymmetric masses (including a component with a mass between those of neutron stars and black holes) and the first observation of an intermediate-mass black hole.
Thursday Nov 19, 10:30
Cullan Howlett (University of Queensland)
Colloquium: Testing gravity in the local Universe
The positions and peculiar velocities of low-redshift galaxies encode a wealth of cosmological information. In particular, they enable us to test different gravitational theories on scales far beyond our galaxy by measuring the rate at which clusters, filaments and voids grow. In this talk I will discuss some of the techniques we have developed to access this information using the correlations between the positions and velocities of galaxies. I will then present applications of these techniques to data from a number of surveys including the 2Mass Tully Fisher and 6-degree Field Galaxy surveys. Finally, I will end with some exciting plans for the future including our release of the largest ever constructed peculiar velocity catalogue from the Sloan Digital Sky Survey, and the immense amount of data that will be obtained by the Dark Energy Spectroscopic Instrument.
Tuesday Nov 10, 10:30
Pravir Kumar (Swinburne)
Student Review: Pravir Kumar: mid-candidature review
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Thursday Nov 5, 10:30
Marla Geha (Yale)
Colloquium: The SAGA Survey: Exploring Satellite Galaxies Around Milky Way Analogs
The SAGA Survey will spectroscopically identify satellite galaxies brighter than Mr = −12.3 around one hundred Milky Way analogs at z ∼ 0.01. We recently published our Stage II data release, which included 127 satellites around 36 hosts. The data quadruple the sample size presented in 2017 and significantly increases spectroscopic coverage for very low-redshift galaxies with magnitudes 17 < r < 21 around SAGA hosts, creating a unique data set that places the Local Group in a wider context. I will discuss results from SAGA Stage II on the quenched fraction of satellites, luminosity functions, radial distributions and more, comparing these both to the Milky Way itself
and predictions from simulation.
Thursday Oct 29, 15:00
Shingo Tanigawa (Swinburne)
Student Review: Shingo CoC review
Discovering unusual objects in the early universe using deep learning techniques
Thursday Oct 29, 10:30
Stefano Profumo (UCSC)
Colloquium: What is the Dark Matter?
Four fifths of the matter in the universe is made of something completely different from the "ordinary matter" we know and love. I will explain why this "dark matter" is an unavoidable ingredient to explain the universe as we observe it, and I will describe what the fundamental, particle nature of the dark matter could possibly consist of. I will then give an overview of strategies to search for dark matter as a particle, describe a few examples of possible hints of discovery, and outline ways forward in this exciting hunt.
Tuesday Oct 27, 15:00
Waqas Bashir ()
Student Review: Waqas Bashir's Confirmation of Candidature Review
Password: 675276
Thursday Oct 22, 14:00
Tessa Vernstrom (CSIRO)
Colloquium: Detecting the Magnetised Cosmic Web
On the largest scales there is the cosmic web: voids, clusters and filaments connected in a weblike pattern. Synchrotron emission from the magnetic fields pervading the cosmic web is a fundamental feature of the Universe required by theories of large-scale structure formation. Matter falling into and along filaments of the cosmic web creates shocks, accelerating electrons amplifying magnetic fields and producing synchrotron emission. Detecting this emission and measuring its properties tells us about large-scale structure formation and evolution and the role of cosmic magnetism. However, this synchrotron emission is expected to be faint and diffuse, spread over Mpc scales. Thus direct imaging is challenging, as even with the most sensitive telescopes source confusion and other effects will dominate. Statistical techniques such as cross correlation, image stacking, and the use of Faraday rotation measures can help dig below the noise. I will discuss how these methods work and some of their challenges, the status of detection with current data, and the prospects for detection with future telescopes and surveys.
Thursday Oct 15, 09:30
Katie Auchettl (University of Melbourne)
Colloquium: The imprint of their explosions: Using supernova remnants to understand stellar death
One of the most uncertain aspects related to our understanding of the end points of stellar evolution is the link between the progenitor star and the nature of the supernova explosion that the progenitor will undergo. Even though hundreds of supernovae are discovered each year by optical surveys, these sources are usually too distance to resolve the ejecta and immediate surrounding of the exploded star. However, due to their long lifetimes and close proximity, supernova remnants which are the long lived structures that results from the supernova explosion of either a white dwarf or a massive star, provide us with a unique opportunity to study supernova explosion and dynamics up close and in detail. In this talk, I will highlight some recent advances that have been made in the understanding of supernovae and their progenitors using multi-wavelength studies of supernova remnants.
Tuesday Oct 13, 10:30
Vivek Gupta ()
Student Review: Vivek Gupta's DTR
Thursday Oct 8, 10:30
Shany Danieli (IAS/Princeton)
Colloquium: Diffuse Galaxies as a Probe for Dark Matter
Low mass galaxies provide an essential testing ground for theoretical predictions of cosmology. Their number densities, structures, and internal dynamics can be extremely insightful for studying dark matter on small scales. Recent advances in telescope instrumentation and detection techniques have opened a new window into identifying and characterizing the population of such low surface brightness galaxies. I will discuss the recently identified population of ultra-diffuse galaxies (UDGs) that holds the promise of new constraints on low mass galaxies dynamics, as their spatial extent and often significant globular cluster populations provide probes on spatial scales where dark matter should dominate the kinematics. I will also discuss the dynamics of two UDGs that seems to lack most, if not all, of their dark matter. I will finish by presenting our strategy for finding low surface brightness galaxies as part of the recently completed Dragonfly Wide Field Survey, covering 330 sq. deg., in the GAMA and Stripe 82 fields.
Tuesday Oct 6, 10:30
Hao Ding ()
Student Review: Hao Ding Mid-candidature review
Meeting ID 952 7617 3918
Passcode 900194
Thursday Oct 1, 10:30
Daniel Price (Monash University)
Colloquium: Where did I come from?
I will present the birds and the bees of planet formation, or at least what we have learnt from recent observations of protoplanetary discs with ALMA and the Very Large Telescope.
Tuesday Sep 29, 10:30
Nandini Sahu (CAS/OzGrav)
Student Review: Nandini Sahu DTR: Supermassive black hole mass scaling relations
Show your support for our PhD student Nandini Sahu, who will report on her hard work over the past 3 years into the supermassive black hole (SMBH) scaling relations, derived using modern galaxy image decomposition techniques, with implications for SMBH/galaxy coevolution and long-wavelength gravitational waves. (zoom pwd: 165271)
Thursday Sep 24, 10:30
Hanae Inami (Hiroshima University)
Colloquium: Constraining the Molecular Content in the Hubble Ultra Deep Field using the ALMA Spectroscopic Survey
The peak of galaxy growth around z~1-3 could be due to either a large supply of molecular gas for forming stars or a mechanism which causes high efficiency in star formation, or a combination of these two processes. The ALMA Spectroscopic Survey (ASPECS) project has conducted a spectroscopic survey over the entire frequency range of ALMA Bands 3 and 6 in the Hubble Ultra Deep Field (HUDF) to carry out an unbiased search for CO emission, which traces the fuel of star formation. In this talk, I will first introduce the ASPECS project and show an overview of its recent results. Then I will present more detailed results regarding a new CO stacking analysis. This analysis is performed based on spectroscopic redshifts determined by another unbiased spectroscopic survey using the optical integral field spectrograph instrument MUSE (Multi Unit Spectroscopic Explorer). Using the MUSE data we recover most of the CO emission in our deep ALMA observations through stacking, which demonstrates the synergy between volumetric surveys obtained at different wavebands.

Hiroshima University, where I am based, is also pursuing time domain astronomy. We own a 1.5m telescope which is designed for fast followup observations of transient objects. At the beginning of my talk, I would like to briefly introduce some of our projects conducted at the Higashi-Hiroshima Observatory.
Wednesday Sep 23, 10:30
Daniel Berke (CAS)
Student Review: Daniel Berke's Draft Thesis Review
Zoom password: 010799
Tuesday Sep 22, 10:30
Dexter Hon (Swinburne)
Student Review: Dexter Hon MCR: Compact massive spheroids at z=0
Compact massive spheroids in the local Universe
Thursday Sep 17, 14:30
Barak Zackay (Weizmann institute of science)
Colloquium: Detecting Gravitational Waves Using the public LIGO-VIRGO data: Doubling the sample of Binary Black Hole Mergers
The LIGO-VIRGO data presents a magnificent opportunity for exploring the uncharted territory of binary compact objects. We have developed an independent analysis pipeline for analyzing the public LIGO-VIRGO data from the first two observing runs. We have developed several novel techniques, and revisited all the choices essential for such an analysis. The resulting improvement (comparing to the LIGO-VIRGO official analysis) amounts to doubling the probed volume for binary black holes, and as a result, doubled the sample of detected events.

Among the newly discovered events are:
An event (GW170121) with substantial negative effective spin,
An event (GW151216) with maximal effective spin, inconsistent with dynamical formation.
An event (GW170817A) with source frame total mass of about a hundred solar masses, constraining the existence of any potential upper mass cutoffs.

I will also discuss the prospects for detecting systems of lensed GW events, what we learn from them, and present an intriguing candidate. Last, I will briefly mention current and future projects including some future directions in GW astrophysics.
Tuesday Sep 15, 10:30
Poojan Agrawal (Swinburne)
Student Review: Draft Thesis Review
Thursday Sep 10, 10:30
Khaled Said Soliman (UQ)
Colloquium: Constraining the cosmological parameters with peculiar velocities
The deviation of a galaxy velocity from the mean value set by Hubble-Lemaitre law is said to be the galaxy's peculiar velocity. Comparing these peculiar velocities to the surrounding density field is a unique way to constrain the growth rate of cosmic structure which is one observational way to distinguish GR from alternative gravity theories. I will discuss our recent measurements of the growth rate of fluctuations and the fluctuations on 8 Mpc/h scales, as well as for the Hubble parameter based on our approach. I will also compare our recent measurements with other low and high redshift probes.
Thursday Sep 3, 10:30
Chris Pinte (Monash University)
Colloquium: Observing Planet Formation
We still do not understand how planets form, or why extra-solar planetary systems are so different from our own solar system. Recent observations of protoplanetary discs have revealed rings and gaps, spirals and asymmetries. These features have been interpreted as signatures of newborn protoplanets, but the exact origin is unknown, and remained until recently poorly constrained by direct observation. In this talk, I will show how high spatial and spectral resolution ALMA observations can be used to detect embedded planet in their discs, and discuss the implications on our understanding of planet formation.
Tuesday Sep 1, 10:30
Student Review: Ayushi Mandlik CoC
Password: 282788

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Thursday Aug 27, 10:30
Claude-André Faucher-Giguere (Northwestern University)
Colloquium: How do galaxies form? New insights from the FIRE simulations
Galaxies are remarkably diverse in their properties, ranging from irregular to disky to elliptical in morphology, and from blue to red in color. At the same time, when analyzed systematically, galaxy populations exhibit striking regularities, with clear trends with mass and redshift. How does this "regular complexity" emerge from the hot Big Bang? I will present results from the FIRE simulations which shed some light onto the processes that shape galaxies. The FIRE zoom-in simulations resolve the multiphase interstellar medium of galaxies and model several different feedback processes (including Type II/Ia supernovae, stellar winds, and radiation) while including the cosmological environment. I will highlight recent results on the formation of galactic disks, the "burstiness" of star formation, galactic winds, and the growth of supermassive black holes. Our new results indicate that transitions in the properties of each of these important phenomena can be simultaneously explained by a phase transition (virialization) in the inner circumgalactic medium, and arise from the interplay between feedback energy produced on small scales and the physics of halo gas on larger scales.
Tuesday Aug 25, 10:30
Dian Triani ()
Student Review: Pipit's Draft Thesis Review
Zoom meeting id is 921 0095 1031, password is 567769
Wednesday Aug 19, 13:30
Pol Gurri (CAS)
Student Review: Precision weak lensing (Draft Thesis Review)
I'll present an end-to-end methodology to measure the effects of weak lensing on individual galaxy-galaxy systems exploiting their kinematic information. Using this methodology, I have measured a shear signal in the velocity fields of 21 weakly- lensed systems. I'll present a way to find the dispersion in our measurement due to a dispersion in the SHMR and a new avenue to constrain the dispersion in the SHMR.

See you there!
Tuesday Aug 18, 10:30
Burak Dogruel (CAS)
Student Review: Fundamental Scaling Relations Among Galaxies in the Local Universe (Confirmation)
Tuesday Aug 11, 10:30
Hasti Nateghi (Swinburne)
Student Review: Confirmation of Candidature - Hasti Nateghi
Thursday Aug 6, 13:30
Marcus Lower ()
Student Review: Marcus Lower Mid-Candidature review
Tuesday Aug 4, 10:30
Cherie Day ()
Student Review: Cherie Day Draft Thesis review
Zoom meeting id: 923 3117 5889, password 445333
Tuesday Jul 28, 10:30
Ellert vd Velden ()
Student Review: Ellert DTR
Thursday Jul 23, 10:30
Christian Herenz (ESO, Santiago)
Colloquium: Exploring the high-redshift Lyman-alpha universe with MUSE
The MUSE integral field spectrograph at ESOs Very Large Telescope "Antu" has delivered an unparalleled view of the Lyman alpha emitting galaxy population in the high-redshift universe. This talk starts by providing an overview of the processes that create and shape hydrogen Lyman alpha emission from galaxies. Here the focus will not only be on theoretical aspects but I will also present empirical insights that have been obtained from low-z star-forming galaxies thanks to the UV capabilities of the Hubble Space Telescope. I then introduce the various MUSE surveys and their publicly available datasets. To showcase some scientific highlights of those datasets I will present results from luminosity function studies as well as studies of the low-surface brightness Lyman alpha emission from the circum-galactic media of galaxies at z>3. I will conclude the talk with recent results from the so far deepest MUSE observations of a z~3.1 Lyman alpha blob.
Wednesday Jul 22, 14:00
Rahul Sengar (Swinburne)
Student Review: Rahul Sengar 24month review
Rahul will talk about his PhD research on pulsar searching.
Tuesday Jul 21, 10:30
Debatri Chattopadhyay ()
Student Review: Draft Thesis Review
Thursday Jul 16, 10:30
Nikhil Sarin (Monash University)
Colloquium: Observational consequences of binary neutron star merger remnants
The first neutron star merger observed with gravitational waves and in electromagnetic radiation confirmed that binary neutron star mergers are the progenitors of at least some short gamma-ray bursts. The multi-messenger observations have been used to a probe a lot of fundamental physics, however, despite the wealth of observations the fate of the remnant of GW170817 is still uncertain. I will give an overview of binary neutron star mergers focussing on the nature of the remnant from observations of short gamma-ray bursts and theoretical considerations. I will discuss the implications of these observations on the nuclear equation of state, neutron star dynamics and gamma-ray bursts.
Tuesday Jul 14, 10:30
James Edaile (Swinburne)
Student Review: James Esdaile Draft Thesis Review

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Thursday Jul 9, 10:30
Irene Shivaei (Steward Observatory)
Colloquium: Dust in Galaxies at High Redshifts
One of the mysterious components of galaxies is dust. Dust not only plays an important role in the physics and chemistry of the ISM, but also shapes our views of galaxies by absorbing and scattering UV and optical light and re-emitting it in longer IR wavelengths. Despite its importance, we know very little about dust at high redshifts. I use multi-wavelength facilities, including Hubble, Keck, Spitzer, and ALMA to trace dust in absorption and emission at redshift of z~2, the peak epoch of cosmic star formation activity. In this talk, I will highlight our recent results on constraining the dust attenuation curve and the mid-IR aromatic bands strength at redshift of z~2 and the implications for future JWST observations of high-redshift galaxies. Moreover, as a member of the JWST MIRI GTO science team, I will briefly discuss our extragalactic survey to probe the mid-IR dust emission at high redshifts.
Thursday Jul 2, 10:30
Jan J. Eldridge (University of Auckland)
Colloquium: Some of the things binary stars do....
Most of the stars in the Universe are not single like our Sun but in binary stars systems. A binary star is composed of two stars in orbit around each other, as they age they can "get-in-each-others" way and experience very different evolution to that our stars like our Sun. Only over the last decade it has become clear that to accurately understand the Universe we need to take account of these interacting binary stars. In my talk I will go over a few examples showing how understanding binary stars allows us to understand the appearance of galaxies, the diversity of supernovae, the production of the most abundant and rarest elements and the production of gravitational wave transients.
Tuesday Jun 30, 10:30
Simon Goode (Swinburne)
Student Review: Simon Goode's CoC Review
Thursday Jun 18, 10:30
Kathryn Ross (Curtin University)
Colloquium: Balancing the Equation: The #IncludeHer Movement
Aspiring women in Science, Technology, Engineering and Mathematics (STEM) fields need to be shown potential careers are achievable and given visible role models. However, currently in NSW, all students undertaking a year 11 or year 12 Science course as part of their HSC are only shown a sexist representation of scientists. After this discovery in 2018, the #IncludeHer movement was started to see this biased representation in NSW fixed. Since then, it has grown to a national campaign and sparked conversations with the NSW Education Standards Authority, Sarah Mitchell, the Minister for Early Education and Childhood Learning and over 1,800 signatures in a worldwide petition. In this talk, I will outline my journey running this campaign and the outcomes it is working towards. This talk is to start the conversation about how we represent scientists to young students and discuss plausible solutions we can begin implementing immediately.
Thursday Jun 11, 10:30
Lorenzo Spina (Monash University)
Colloquium: Understanding our Galaxy: charting a path forward
Galaxies are factories that convert gas into stars, and in the process they constantly evolve. Atoms are fused into heavier ones by stars and then are dispersed into space, where they become the building blocks for a next generation of stars. It is possible to link this chemical build up to the history of galaxies, by studying the chemical makeup of stars in our own Galaxy. However, our comprehension of how the Milky Way evolves and how it operates as a machine is still incomplete. Filling this gap in knowledge would significantly advance our understanding of cosmology, nuclear physics, stellar evolution, and the sequence of events that led to our existence on planet Earth. In this talk I will present some recent results on the chemical evolution of the Milky Way disk and I will focus on key open questions that need to be addressed over the current decade.
Thursday Jun 4, 10:30
Pierluigi Cerulo (Universidad de Concepcion)
Colloquium: The Morphological Transformation of Galaxies as a function of environment
The evolution of galaxies is driven by complex physical mechanisms that may have internal or environmental origins. As time passes galaxies become less star-forming and tend to acquire elliptical or lenticular morphologies. We have embarked in a simultaneous study of morphology and star formation in cluster and field galaxies with the aim of investigating the relationships between star-formation quenching and morphological transformations as a function of environment. In this talk I shall present the results of a study conducted on galaxies in the CLASH and CANDELS surveys at redshifts 0.2 < z < 0.9. By dividing galaxies into star-forming and quiescent we find that quiescent ellipticals are more abundant in clusters than in the field. Regardless of the environment, we observe an increase in the fraction of quiescent disc galaxies at low redshifts, supporting the notion that star-formation quenching precedes morphological changes, at least at low stellar masses. Star-forming field galaxies are mostly late type discs, while in clusters they present a diverse morphological composition with a non-negligible fraction of star-forming ellipticals that is detected in low-redshift clusters. I will discuss the implications of our results in the general context of galaxy evolution.
Tuesday Jun 2, 15:30
Geray Karademir ()
Student Review: Using Clustering Redshifts to Measure Galaxy Evolution
Confirmation of Candidature review for Geray Karademir.
Zoom password: 137484
Thursday May 28, 10:30
Laurie Rousseau-Nepton (CFHT)
Colloquium: The SIGNALS legacy survey: On the birth of stars in the nearby Universe
October 2018 marked the beginning of a new large program at the Canada-France-Hawaii Telescope: SIGNALS, the Star-formation, Ionized Gas, and Nebular Abundances Legacy Survey. During the next four years and with 55 nights of telescope time in hands, our collaboration is observing more than 50,000 extragalactic HII regions located in different galactic environments using the Imaging Fourier Transform Spectrograph, SITELLE. In order to build such a sample, we cover 40 galaxies that are actively forming stars within a distance of 10 Mpc. SITELLE, with its FOV of 11 arcminutes and its 4 million spaxels, is the perfect instrument to survey these often extended objets. We are gathering spectral information over the strong emission lines of the visible (i.e. [OII]3727, Hbeta4861, [OIII]4959,5007, [NII]6548,6583, Halpha6563, HeI6678, [SII]6716,6731) with a spectral resolution of 5000 (on Halpha) at a mean spatial resolution of 15 parsecs. Along with ancestry data in the IR and UV, our collaboration aims at studying resolved star-formation activity, understanding the impact of the local environment on the star-formation process, and providing the science community with a unique dataset along with new tools to study star formation. During this presentation, I will introduce this ambitious project and will show some preliminary results from the M33 data and other galaxies.
Thursday May 21, 10:30
Joe Burchett (UCSC)
Colloquium: Galaxy ecosystems and the Cosmic Web
Forming new generations of stars in galaxies critically depends on gas flows that can both fuel and deprive galaxies of their precious gas supply. Fresh cold gas must flow in to form new stars, while the explosive deaths of stars and supermassive black holes eject cold and hot gas into a galaxy’s surroundings. All of this is compounded by the fact that galaxies do not live in isolation; they form a veritable ecosystem, exchanging matter and energy, which dramatically impacts the evolution of galaxies therein. I will present observations of gaseous galaxy environments on both small and large scales that reveal this evolution in action, from dwarf galaxies to galaxy groups and clusters to the Cosmic Web. In the immediate vicinity of galaxies, the gaseous halo, or circumgalactic medium (CGM), serves as both a gas reservoir and mediator of all interactions between galaxies and their environments. On the largest scales, the intergalactic medium (IGM) filling the Cosmic Web is the Universe’s storehouse of gas that can feed the CGM and galaxies themselves. With even a little help from slime mold, I will show how we are beginning to reveal how galaxies, their CGM, and the IGM are intimately connected to the Cosmic Web and evolve within their ecosystem context.
Thursday May 14, 10:30
John Chisholm (UCSC)
Colloquium: Peaking below the Lyman Break: Observational constraints and ionizing photon production of massive star populations
Energy and momentum from massive stars drives gas out of galaxies, regulating galaxy growth and cosmic evolution. Perhaps as important, ionizing photons from massive stars generate nebular emission lines and heat dust, which observationally diagnose the physical conditions of galaxies throughout cosmic time. These observations have shed light on the formation and evolution of galaxies, but they are founded upon the ability to determine the properties of the underlying massive star populations. Here, I present a far-ultraviolet stellar population synthesis analysis of 61 star-forming galaxies, both in the local Universe and at redshift 2. I fit their observed far-ultraviolet stellar continua with fully theoretical stellar continuum models to estimate the metallicities, ages, and star formation histories of the massive star populations. These fits predict the production of ionizing photons, which strongly varies from galaxy-to-galaxy. I will discuss the underlying stellar astrophysics that drives these fits and their relation to the inferred stellar properties. I conclude by discussing how the assumed star formation histories, stellar atmospheres, and stellar evolution models impact the production of ionizing photons and explore how certain we can constrain the production of ionizing photons.
Thursday Apr 30, 10:30
Meg Millhouse (University of Melbourne)
Colloquium: A search for gravitational waves from twelve young supernova remnants in Advanced LIGOs second observing run
The Laser Interferometer Gravitational-Wave Observatory (LIGO) has now reported numerous detections of transient gravitational-wave events from systems of merging binary black holes or neutron stars. However, many more potential gravitational-wave sources exist. In addition to looking for transient signals, there are a number of searches for persistent, quasi-monochromatic gravitational-wave emission from rapidly rotating neutron stars. Young supernova remnants containing neutron stars are a particularly promising source of these continuous gravitational waves. In this talk I will go over sources of continuous gravitational wave emission, outline current search methods and challenges, then present the results of a recent search for gravitational waves targeting twelve young supernova remnants.
Tuesday Apr 28, 10:30
Arianna Dolfi ()
Student Review: Mid-term review
Mid-term review
Thursday Apr 23, 10:30
Nicha Leethochawalit (University of Melbourne)
Colloquium: Using mass-metallicity relations from quiescent galaxies to constrain stellar feedback models
The correlation between stellar mass and metal abundance (or MZR, the mass-metallicity relation) reflects the balance between galactic feedback and galactic gravitational potential. We present stellar MZRs based on the stellar metallicities of individual quiescent galaxies in the Cl0024 and MS0451 galaxy cluster at redshifts 0.4 and 0.54 respectively. The measurements were made via full-spectrum stellar population synthesis models. The lower limit of our stellar mass range is log[M/Msun]=9.7. To our knowledge, this is the lowest galaxy mass at which individual stellar metallicity has been measured beyond the local universe. We detect an evolution of the stellar MZR with observed redshift when the metal is iron (Fe). We do not detect any significant evolution with observed redshift when the metal is Magnesium (Mg). We use a simple analytic chemical evolution model to constrain average outflow that these galaxies experience over their lifetime, via the calculation of mass-loading factor. We find that the average mass-loading factor is a power-law function of galaxy stellar mass. The measured mass-loading factors are consistent with the results of other observational methods for outflow measurements and with the predictions where outflow is caused by star formation feedback in turbulent disks.
Tuesday Apr 21, 10:30
Ryan Turner ()
Student Review: Ryan Turner CoC talk
Thursday Apr 16, 10:00
Danielle Berg (Ohio State University)
Colloquium: Bridging Galaxy Evolution Across Cosmic Time: Tracing the Interplay Between Massive Stars and Their Surrounding Gas with Spectro
The first stars and galaxies initiated the epoch of reionization (EoR) and provided the seeds from which all galaxy evolution grew. Knowledge of the properties of these galaxies are needed to understand ionizing photon production and escape, and will provide the crucial missing link needed to weave a coherent picture of galaxy evolution. I will present several programs that are establishing the needed framework to interpret galaxies from z~0‒10, bridging the present-day and early universe. These programs use multi-wavelength spectroscopy to disentangle the spectral signatures that characterize the interplay between massive stars and their surroundings, and allow us to interpret how radiative processes shape galaxies. I will show how precise measures of the stellar and nebular properties of both nearby and distant lensed galaxies directly link the ionizing stellar populations with the baryon+metal feedback cycle and the conditions of ionizing photon production and escape. My studies provide a detailed foundation of the diversity of local star-forming galaxies with which to interpret cosmic evolution, as well as unique laboratories of nearly pristine gas in which to test conditions analogous to the first galaxies. In preparation for the coming UV window onto the early universe with the advent of the James Webb Space Telescope and the extremely large telescopes, I will introduce the COS Legacy Archival Spectroscopic SurveY (CLASSY) - an upcoming large Hubble Space Telescope program that will produce the first high-resolution UV spectral atlas of star-forming galaxies. CLASSY will calibrate new tools that will allow us to completely describe the stars and interstellar medium in galaxies across redshift, setting the stage to study cosmic origins, ionizing production, and the evolution of galaxies in a unified framework.
Tuesday Apr 7, 10:30
Christian Lehmann (CAS)
Student Review: Christian Lehmann's Confirmation of Candidature review
Time: Apr 7, 2020 10:30 AM Canberra, Melbourne, Sydney

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Meeting ID: 965 171 645
Thursday Mar 26, 10:30
Tim Roth (imachination projects)
Colloquium: Music of the Spheres and the colourful Birth of Astrophysics
How does the Ancient Music of the Spheres sounds under the conditions of Astrophysics of the 21th century? The Heaven’s Carousel presented from 20 March – 6 April in occasion of the World Science Festival and Curiocity Brisbane gives a contemporary answer. The kinetic artwork was developed by Tim Otto Roth in collaboration with Hubble Space Telescope. The 36 illuminated speakers rotating over the heads of the audience create a giant sound accelerator playing with the Doppler Effect and echoing the accelerated expansion of the universe as Adam Riess pointed out at the premiere 2014 in Rome.

Tim Otto Roth will speak not only as artist about his numerous astrophysical collaborations, but in his double role as art and science historian he will talk also about the strong tie between colour observation of the celestial spheres and the birth of astrophysics in the 19th century.
The highly sophisticated concept of colour in astrophysics inspired by colorimetric observations and the spectroscopic decomposition of starlight is complementary to the colour experiments of (Neo-)Impressionism emerging at about the same time. As immediate physical effect spectra challenge our concepts of image and visualization, so spectra in astronomy are at least as unsettling as the colourful explorations by the French painters.

Tim Otto Roth (*1974) is a German conceptual artist, composer and scholar. He is known and awarded for his large art & science projects in public space including scientists of top research institutions around the world, as ESO, CERN (Geneva) or IceCube in Antarctica. He considers his work as a plea for a physics of art. As art and science historian he published in 2015 the definite book »Cultural History of Shadow Pictures« (Fink).
Thursday Mar 19, 10:30
Geoff Bryan ()
Student Review: Geoff Bryan's DTR
Online via Zoom:

Panel member; zoom link booked for 2 hours.

At this stage, Geoff plans to use the AR Tearoom to deliver his talk
Thursday Mar 19, 14:00
Mohsen Shamohammadi (Swinburne)
Student Review: Mohsen CoC review
Mohsen will give his CoC review on Millisecond pulsar timing with Parkes and MeerKAT.

Zoom link: Hi there,

Matthew Bailes is inviting you to a scheduled Zoom meeting.

Time: Mar 19, 2020 02:00 PM Canberra, Melbourne, Sydney
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Meeting ID: 671 742 743
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Meeting ID: 671 742 743
Tuesday Mar 17, 10:00
Student Review: Chandra draft thesis review

Time: Mar 17, 2020 10:00 AM Canberra, Melbourne, Sydney
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Meeting ID: 515 150 872
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Meeting ID: 515 150 872
Thursday Mar 12, 10:30
Camila Correa (UvA)
Colloquium: Morphological transformations in the local Universe: an observational and theoretical perspective
In this talk I will summarise recent results of the dependence of the galaxy stellar-to-halo mass relation on galaxy morphology. I use data from the Sloan Digital Sky Survey DR7 with morphological classifications from Galaxy Zoo, and also compare with the EAGLE cosmological simulation, to draw a coherent physical picture of the different evolutionary paths of discs and ellipticals. I will also explore possible scenarios of galaxies undergoing morphological transformation and quenching. To finalise I will discuss the limitations of current simulations such as EAGLE, and introduce the ongoing simulation project of EAGLE-2.
Wednesday Mar 11, 10:30
Brodie Norfolk ()
Student Review: Brodie Norfolk's CoC
Tuesday Mar 10, 10:30
Bron Reichardt Chu ()
Student Review: Bron Reichardt Chu's CoC
Tuesday Mar 3, 10:30
Sara Webb ()
Student Review: Sara Webb MCR
Sara's mid-candidature review
Thursday Feb 27, 10:30
Daniel Ceverino (Universidad Autonoma de Madrid )
Colloquium: Simulations at the Dwarf Scale: From Violent Dwarfs at Cosmic Dawn and Cosmic Noon to Quiet Discs today
Dwarf galaxies with stellar masses of 10^9 Msun can be explored at high and low redshifts and they give a glimpse of the different conditions of galaxy formation at different epochs. Using a large sample of about 300 zoom-in cosmological hydrodynamical simulations of galaxy formation I will briefly describe the formation of dwarfs at this mass scale at 3 different epochs: cosmic dawn, cosmic noon, and today. I will describe the FirstLight simulations of first galaxies at redshifts 5-15. These first dwarfs have extremely high star formation efficiencies due to high gas fractions and high gas accretion rates. At cosmic noon, z = 2, galaxy formation is a violent process. The VELA simulations have generated a set of dispersion-dominated dwarfs that show an elongated morphology due to their prolate dark-matter halos. Between z =1-0, the AGORA simulation shows the formation of a low-mass disc due to slow gas accretion.
Tuesday Feb 25, 10:30
Gurvarinder (CAS)
Student Review: Gurvarinder CoC
Thursday Feb 20, 10:30
Prof Sukyoung Yi (Yonsei University Korea)
Colloquium: The origin and fate of the discs of spiral galaxies from numerical simulations
I will present new results on the formation and fate of discs of spiral galaxies from the New Horizon and Galactica simulations. The high-resolution simulations (>40pc) reveal the history of disc settling, build-up, and fading in great detail and provide hints to the origin of the thin and thick discs.
Tuesday Feb 18, 10:30
Grace Lawrence (Swinburne)
Student Review: Grace Lawrence CoC
Grace Lawrence CoC review talk on detecting dark matter, all welcome
Thursday Feb 13, 10:30
Helga Denes (Astron)
Colloquium: The first seven months of the Apertif Imaging Survey
Apertif is the new phased-array feed receiver system on the Westerbork Synthesis Radio Telescope (WSRT). The substantially increased field of view of the telescope makes Apertif a great survey instrument. In July 2019, Apertif started survey observations for a two-tiered imaging survey, with a shallow and medium-deep component and a time domain survey searching for new (millisecond) pulsars and fast radio bursts (FRBs). The main science goals of the Imaging Survey are: the role of environment and interaction on galaxy properties, finding the smallest galaxies, connecting cold gas to AGN, understanding the faint radio population, and studying magnetic fields in galaxies. After a proprietary period, all survey data products will be publicly available through the Apertif Long Term Archive (ALTA, I will describe the first seven months of the Imaging Survey, where the team is observing and automatically processing the data to produce radio continuum images, polarisation images, and HI (neutral hydrogen) line cubes. I will show examples of the survey data and highlight the first science results from the survey.
Tuesday Feb 11, 10:30
Juan Espejo (CAS)
Student Review: Juan Espejo Confirmation of Candidature review - The evolution of galaxy Angular Momentum across cosmic time

The role of angular momentum in the evolution of star forming galaxies


The age of the Universe at which star formation peaks is interesting, angular momentum (j) has been measured to be low and gas fractions (f_gas) are high (compared to local analogues). Both j and f_gas play an important role in the evolution of disk galaxies to the grand design spirals we observe today and so it is important to measure them accurately. Measuring j at high redshift is particularly difficult, one needs deep observations in both infrared photometry (stellar mass distribution) and integral field spectroscopy (emission line kinematics) in order to get an accurate description of the angular momentum content. Currently, most high-z IFS data are natural seeing (NS) limited, which prevents accurate morphological classification, introduces artefacts and hides small scale kinematic structures that affect the real shape of the rotation curves. On the other hand, adaptive optics (AO) assisted observations improve resolution but suffer from SN loss. One way to account for this is to combine data at the different resolutions: i) AO high resolution data for the inner parts where signal is enough to prevail over the SN loss introduced by the AO correction (and where the rotation curve rises rapidly) and ii) NS low resolution data for the outer parts since SN is high (and where the rotation curve has already flattened). We have analysed a sample of 10 galaxies with the combination method at z∼1.5 and z∼2 (the largest sample at high-z with combined j measurements to our knowledge) from Keck/OSIRIS + VLT/KMOS+SINFONI + HST and we have explored the capabilities of applying the combination method such as a decrease in uncertainty and a more realistic determination of shape and morphology for each galaxy.
Thursday Feb 6, 10:30
Andy Bunker (University of Oxford)
Colloquium: Exploring the high redshift Universe with the James Webb Space Telescope
The James Webb Space Telescope (JWST) will provide a great opportunity to explore
high redshift galaxies, and understand the role of galaxies in the reionization
of the Universe. I will present our observational plans for the Guaranteed Time
Observations of the NIRSpec Instrument Science Team, including those co-ordinated with the NIRCam
Team as part of the JADES survey. Determining the UV luminosity function to faint
magnitudes, coupled with more accurate determinations of the escape fraction (from
observations of the Balmer lines and UV continuum), will address the ionizing photon budget
from galaxies. The census of the fraction of high redshift star-forming galaxies with Lyman alpha in
emission will constrain the neutral fraction of the IGM at z>6, and the size of the ionized bubbles,
and the study of rest-UV absorption lines and nebular emission will shed light on the outflows
and the role of the circum-galactic medium. Working at between 1 and 5 microns, NIRSpec on JWST
has the capability to explore the star formation rates, metallicities and IGM surroundings of
galaxies within the epoch of reionization.