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Colloquia Series

For more information on colloquia at the Centre for Astrophysics and Supercomputing please contact Dr. Simon Stevenson and Dr. Stefan Osłowski ()

Swinburne Virtual Reality Theatre
AR Building, Room 104
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2018 Colloquia

Tuesday Jun 12, 10:30
Daniel Berke ()
Student Review: Daniel Berke's confirmation of candidature review
Thursday May 17, 10:30
Rhea-Silvia Remus (University Observatory Munich)
Colloquium: TBC
Thursday May 10, 10:30
Sarah Leslie (MPIA)
Colloquium: TBC
Tuesday May 8, 10:30
Cherie Day ()
Student Review: Cherie Day Confirmation of Candidature Review
"Localising the source of Fast Radio Bursts with UTMOST-2D", 6 month review talk.
Thursday May 3, 10:30
Nell Byler (ANU)
Colloquium: Self-consistent UV emission and absorption line diagnostics
UV diagnostics are critical for the study of high-redshift galaxies, given that commonly-used optical emission line diagnostics become observationally unavailable as they redshift out of wavelength regimes accessible from the ground. UV emission in galaxies is dominated by flux produced by young massive stars, along with line and continuum emission from ionized gas in the ISM. In this work, I assess the diagnostic potential of both absorption and emission features in the UV, using models that simultaneously and self-consistently consider stellar and nebular emission. I measure the metallicity sensitivity of established UV stellar absorption indices, and identify those that include a significant contribution from nebular emission. I identify combinations of strong emission lines that constrain metallicity and ionization parameter, and develop UV versions of the canonical “BPT” diagram. For nebular emission lines that overlap with known stellar wind features like C IV λλ1548,1551, I quantify the relative contribution from nebular and stellar emission to line ratios. I evaluate the diagnostics against observations of local galaxies and galaxies at high redshift and summarize the best diagnostic choices and the associated redshift range for low-, mid-, and high-resolution rest-UV spectroscopy in preparation for the launch of JWST.
Thursday Apr 26, 10:30
Angel Lopez-Sanchez (AAO)
Colloquium: TBA
Thursday Apr 19, 10:30
Leo Alcorn - TBC (Texas A&M University, USA)
Colloquium: TBC
Tuesday Apr 17, 10:30
Matt Agnew ()
Student Review: Matt Agnew's 30 month reivew
Thursday Apr 12, 10:30
Dimitri Veras (University of Warwick, UK)
Colloquium: The growing field of post-main-sequence exoplanetary science
Connecting planetary systems at different stages of stellar evolution helps us understand their formation, evolution and fate, as well as provides us with crucial insights about their dynamics and chemistry. Post-main-sequence stars -- pulsars, white dwarfs and giant branch stars -- all host planetary systems, which often include remnant debris discs. Here I provide a review of our current knowledge of these systems. I show how this interdisciplinary field incorporates several facets of stellar physics and chemistry as well as solar system physics and chemistry, and detail simulation-based efforts to understand the big picture.
Tuesday Apr 10, 10:30
Debatri Chattopadhyay (Swinburne University of Technology)
Student Review: Debatri Chattopadhyay
Confirmation of Candidature
Wednesday Apr 4, 10:30
Richard McDermid & Francois Rigaut (Macquarie University)
Colloquium: TBA
Thursday Mar 29, 10:30
Vid Irsic (University of Washington, USA)
Colloquium: Small scale structure of the IGM: A Dark Matter Tale
The intergalactic medium (IGM) plays a unique role in constraining the (small scale) matter power spectrum, since the low-density, high redshift IGM filaments are particularly sensitive to the small scale properties of dark matter. The main observable manifestation of the IGM, the Lyman-alpha forest, has provided important constraints on the linear matter power spectrum, especially when combined with cosmic microwave background data. This includes, most notably, the tightest constraints on warm dark matter (WDM) and fuzzy dark matter (FDM) models, that I will present in this talk.
Tuesday Mar 27, 10:30
Pipit Triani ()
Student Review: Confirmation of Candidature
Thursday Mar 22, 10:30
Eva-Maria Mueller (University of Portsmouth)
Colloquium: TBA
Tuesday Mar 20, 10:30
Sarah Hegarty ()
Student Review: Pre-Submission Review
Wednesday Mar 14, 10:30
George Djorgovski (Caltech)
Colloquium: Quasars in the Time Domain
Quasars play a key role in our understanding of the physical universe and its major constituents. Variability is one of their key observable characteristics, and it is present at all wavelengths and at all time scales probed so far. It reflects directly the physics of their fueling and beaming, and offers a spectrum-independent method for quasar discovery that bypasses many selection effects. The field is being transformed by the large synoptic sky surveys and the resulting archives of light curves, that offer unprecedented opportunities for the systematic studies of quasar variability. I will describe several such projects, based mainly on the CRTS survey archive, including: a novel characterization of the stochastic variability of quasars, a discovery of a population of quasars with a periodic variability interpreted as a signature of the long-predicted supermassive black hole binaries, the most efficient method to date for a selection of quasar candidates, the discovery of megaflares in their light curves, a search for outliers in the variability parameter space that revealed interesting phenomena, including a population of type-changing quasars, etc.
Tuesday Mar 13, 10:30
Renee Spiewak (Swinburne University of Technology)
Student Review: Renee Spiewak

Renee Spiewak 18 month review.

Searching for and timing millisecond pulsars.
Thursday Mar 8, 10:30
Mike Hudson (University of Waterloo, Canada)
Colloquium: Galaxies and Dark Matter Seen Through a Gravitational Lens
The evolution of galaxies is linked to the growth and accretion histories of their host dark matter haloes. Weak gravitational lensing allows us to measure the evolution of their dark matter haloes, as well as the larger cosmic web that these haloes inhabit. I will review recent results from weak gravitational lensing and other methods that allow us to probe the dark matter content of the Universe on the scale of galaxies and so provide new insight into the processes that shape the evolution of galaxies. I will also discuss our recent detection of dark matter in the filaments of the cosmic web between galaxies. I will conclude by highlighting prospects from upcoming ground-surveys, and satellite missions.
Tuesday Mar 6, 10:30
Ellert vd Velden ()
Student Review: Student Review: Ellert vd Velden - Confirmation of Canditature
Ellert vd Velden 6 month PhD Review / Confirmation of Canditature
Thursday Mar 1, 10:30
Rachael Livermore (University of Melbourne)
Colloquium: Harnessing the Power of Gravitational Lensing
The magnifying power of gravitational lensing allows us to study distant galaxies in unprecedented detail. At moderate redshifts (1 < z < 5) the spatial magnification allows us to examine the kinematics and morphologies of ‘normal’ star-forming galaxies, revealing the processes that lead to the clumpy star formation observed in this epoch. At the highest redshifts (6 < z < 10), the flux magnification from lensing allows us to directly observe dwarf galaxies in the first billion years of the Universe, probing the faint end of the luminosity function where the majority of the ionizing photons that contribute to reionization originate. I will also discuss prospects for JWST in studying the first galaxies and the epoch of reionization.
Tuesday Feb 27, 10:30
Aditya Parthasarthay (Swinburne University of Technology)
Student Review: Aditya Parthasarthay
Aditya 18 month review.
Thursday Feb 22, 10:30
Roland Bacon and Johan Richard (Centre de Recherche Astrophysique de Lyon, France)
Colloquium: Science prospects with MUSE at the VLT
The Multi-Unit Spectroscopic Explorer (MUSE) is an integral field spectrograph with unique capabilities on the Very Large Telescope. With its high sensitivity and by providing a complete view of the optical spectrum over 1 arcmin2 it has been a tremendous breakthrough in the way galactic and extragalactic observations are performed. We will present a few examples where MUSE's transformational science capabilities are demonstrated. The success of MUSE calls for new ideas for the next generation of VLT instruments, and we will present the concept of a blue-MUSE: a wider field of view, higher resolution, blue-optimised version of MUSE.

Slides: Keynote
Slides: PDF
Tuesday Feb 20, 10:30
Pol Gurri (Swinburne University of Technology)
Student Review: TBC
Confirmation of Candidature
Thursday Feb 15, 10:30
Themiya Nanayakkara (Leiden University, The Netherlands)
Colloquium: Hunting for the first stars I: Attempts to demystify He II with MUSE
In the quest for identifying pop-III stars, the most sought-after emission line is He II, however, stellar population models are unable to accurately predict the He II features while being consistent with other emission line diagnostics. To produce He II ionizing photons, stellar populations require sources of hard ionizing radiation with energies >= 54.4 eV and sources such as AGN, shocks, X-Ray binaries, stellar rotation and/or binary stellar evolution, and post-AGB stars have been suggested as possible contributors. To accurately identify relative contributions from these wide variety of sources, high signal-to-noise spectra with rest-frame UV/optical coverage and advanced stellar population/photoionization models are required.

The VLT/MUSE GTO program has obtained deep ~10-30h exposures of the Hubble legacy fields yielding rest-UV spectra of galaxies at z~2-6. In this talk I will present recent results of the MUSE program, where we compare the z=2-4 He II emitters with expectations from photoionization modelling to explore their stellar population and ISM conditions. I will compare our results with recent results from local samples of high-redshift "analogues" to show the different parameter spaces probed by local and high-redshift galaxies in the rest-UV. I will address the necessity to obtain high signal-to-noise spectra of individual galaxies to model rest UV emission and absorption systems along with auxiliary rest-NIR lines to constrain stellar population properties of galaxies at high-z, which will be aided by combined studies by MUSE and JWST in future.
Tuesday Feb 13, 10:30
Uros Mestric ()
Student Review: mid-candidature
Thursday Feb 8, 10:30
Emily Petroff (ASTRON, The Netherlands)
Colloquium: Detection and follow-up of fast radio bursts
Fast radio bursts (FRBs), bright millisecond duration radio transients, are quickly becoming a subject of intense interest in time-domain astronomy. FRBs have the exciting potential to be used as cosmological probes of both matter and fundamental parameters, but such studies require large populations. Advances in FRB detection using current and next-generation radio telescopes will enable the growth of the population in the next few years from 30 to hundreds. Real-time discovery and follow-up, and new studies of the FRB population will provide us with some of the greatest insights in the coming years. I will discuss many observational aspects of the FRB population, including polarisation, searches for multi-wavelength emission, localisation, and repeating FRBs. I will also discuss how our response to these events can inform next generation surveys and pave the way for the enormous number of FRB discoveries expected in the SKA era.