Skip to Content

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
  2019    2018    2017    2016    2015    2014    2013    2012    2011    2010    2009    2008    2007    2006    2005    2004    2003    2002    2001    2000   

2019 Colloquia


Tuesday Jul 30, 10:30
Poojan Agrawal (Swinburne)
Student Review: Poojan Agrawal - Mid-Candidature Review
Tuesday May 14, 10:30
Debatri Chattopadhyay (Swinburne)
Student Review: Debatri Chattopadhyay - Mid-Candidature Review
Wednesday May 1, 10:30
Mamoru Doi (University of Tokyo)
Colloquium: TBA
TBA
Tuesday Apr 30, 10:30
Stephanie Juneau (NOAO)
Colloquium: TBA
TBA
Thursday Apr 25, 10:30
Daniel Reardon (Swinburne)
Colloquium: TBA
TBA
Thursday Apr 11, 10:30
Mark McAuley and Karl Glazebrook (Swinburne)
Colloquium: TBA
TBA
Thursday Apr 4, 10:30
Andreas Burkert (USM Munich)
Colloquium: Declining rotation curves, missing baryons and the origin of turbulence: the puzzling properties of high-redshift disk galaxies
The redshift 2 universe is one of the most interesting epochs of galaxy evolution. It is the era with the peak
of the cosmic star formation rate. Between redshift 3 and 1 the total stellar mass density in galaxies increased from
15% to 70%. It is also the time of rapid galaxy assembly and the epoch where galaxy morphology was determined.

Observations of z=2 star-forming galaxies reveal physical properties that are unparalleled in the z=0 Universe.
Gas-rich, extended, fast rotating and highly turbulent disks have been found with star formation rates that are a factor of 10 to 100
larger than in present-day Milky-Way type galaxies. Kpc-sized, massive gas clumps dominate the appearance of these galaxies. Even more interesting
are recent observations of declining rotation curves in the outer parts of these disks and dynamical masses, inferred from their rotation velocities
that are equal to the observed baryonic mass leaving no room for dark matter.

I will summarize the newest observations and the puzzles and challenges that they generate for our theoretical understanding of cosmic galaxy formation and galactic dynamics.
Thursday Mar 28, 10:30
Amelia Fraser-McKelvie (University of Nottingham)
Colloquium: The complicated lives of disk galaxies: lessons from IFS
Most galaxies consist of a dispersion-dominated bulge region and a regularly rotating disk. These components have built up their mass separately through different processes, yet are evolving together. It has become commonplace to separate the light from bulge and disk regions to better understand their formation and contribution to their host galaxy. The same techniques can also be applied to IFS data of other galaxy components, such as bars and spiral arms. I will detail some of the latest results from the MaNGA galaxy survey, including efforts to study stellar populations in lenticular galaxies within bulge and disk regions, and an investigation into the influence of bars on the secular evolution of disk galaxies.
Thursday Mar 21, 10:30
Vera Patricio (Niels Bohr Institute)
Colloquium: Gravitational Arcs: a closer look at typical z~1 disc galaxies
I will present the analysis of the resolved properties of a sample of highly magnified gravitational arcs. These are typical z~1 disc galaxies that are gravitationally lensed by massive galaxy clusters, which allows us to probe their properties at spatial scales of a few hundreds of parsecs. I will particularly focus on properties derived using MUSE IFU data: the kinematics and ionised gas turbulence of these galaxies, as well as their metallicity. We model both lensing and observational effects to study the intrinsic velocity dispersion and metallicity gradient of these objects. Surprisingly, despite their high turbulence and large star-forming regions, typical of z~1 galaxies, the kinematics and metallicity gradient of these objects is quite similar to what is found in local (mature) discs.
Tuesday Mar 19, 11:00
Aditya Parthasarathy (Swinburne University of Technology)
Student Review: Aditya P
Aditya 33 month review.
Thursday Mar 14, 10:30
Laura Prichard (STSci)
Colloquium: The Evolution of Early-Type Galaxies
Investigating the evolutionary paths of galaxies can reveal valuable information on the conditions of the early Universe, the build-up of the Cosmic Web, the formation of stars and much more. Smooth elliptical early-type galaxies (ETGs) are a "red and dead" population that make up the most massive and old galaxies in the Universe. Their detailed kinematics, revealed through 3D integral-field spectroscopy, has shifted our view of this seemingly homogenous population to a diverse and complex class of galaxy. An increasingly popular theory of ETG evolution shows they could have evolved through two distinct phases: a starburst and steady accretion of gas-poor galaxies. However, a wealth of observational evidence directly conflicts this theory for some ETGs, highlighting the importance of investigating a wider variety of systems through new methods. I will present research that leverages the current leading-edge integral-field instruments to investigate the evolution of ETGs. I look to distant quiescent galaxies in one of the densest regions of the early Universe and at the fossil record of a local galaxy to shed light on some of the unsolved mysteries of how ETGs evolved.
Tuesday Mar 12, 10:30
Marios Karouzos (Nature Astronomy) ()
Colloquium: How to publish (and write) an impactful paper in Nature Astronomy and beyond
Nature Astronomy, launched in January 2017, is a new research journal published by Springer Nature. Sitting alongside our sister journal Nature, we aim to publish high impact research in the fields of astronomy, astrophysics and planetary science. In this talk I will cover the motivation and scope of the journal, the types of manuscripts we publish, the editorial process and what we look for in papers. I will also cover common pitfalls of writing and submitting papers and I will share hints and tips on how to maximize the impact of your paper, from writing an engaging but informative title and a properly contextualized but concise abstract, to structuring your paper in a way that your results are communicated succinctly.
Thursday Mar 7, 10:30
Andrew Cameron (ATNF/CSIRO)
Colloquium: The latest results from the HTRU-S Low Latitude Pulsar Survey: a zoo of new and exciting pulsars
Pulsars, rapidly-rotating and highly-magnetised neutron stars, can be utilised as tools in the study of many aspects of fundamental physical, most notably in the application of binary pulsars to the study of gravitational theories such as General Relativity. The discovery of ever-more relativistic binary systems than those presently known will allow for such tests to probe even deeper into the nature of gravity. Here, I will present results from the processing of 44% of the the HTRU-South Low Latitude pulsar survey (HTRU-S LowLat), the most sensitive blind survey of the southern Galactic plane taken to date. This includes the discovery and long-term timing of 40 new radio pulsars identified through the continued application of a novel “partially-coherent segmented acceleration search” technique, which was specifically designed to discover highly-relativistic binary systems. These pulsars display a range of scientifically-interesting behaviours including glitching, pulse-nulling and binary motion, and appear to comprise a population of generally older, lower-luminosity pulsars as compared to the previously-known population. In addition, I will also present an in-depth report on PSR J1757-1854, the only relativistic binary pulsar to have been discovered in HTRU-S LowLat to date. This extreme double neutron star system (which remains the most accelerated pulsar binary ever discovered) promises to provide new insights into gravitational theories within the coming years.
Tuesday Mar 5, 10:30
()
Student Review: Uros Mestric pre-submission review
Thursday Feb 28, 10:30
Sowgat Muzahid (Leiden University)
Colloquium: MUSEQuBES CGM Surveys: From Low-z Star-forming Galaxies to High-z Lyman-alpha Emitters
Gas accretion and galactic winds are the two most important and yet the most poorly understood ingredients of galaxy evolution models. The physical/chemical conditions of the circumgalactic medium (CGM-- a dynamic, complex, multiphase gas reservoir surrounding galaxies) retain imprints of gas accretion and galactic winds. Moreover, it is now well-established that the metal-enriched, ionized CGM harbors gas and metal masses comparable to those in galaxies themselves and can account for the "missing baryons" in galaxies. Consequently, the CGM has received significant attention from both the theoretical and observational astronomical communities. To this end, we are conducting two major, and by far the largest, surveys on the CGM using ~120 hours of MUSE GTO observations. Our high-z (z > 3) sample comprises ~100 Lyman alpha emitters and the low-z (z < 1) sample comprises ~300 low-mass, star-forming galaxies. We use high S/N spectra of background quasars, obtained with the VLT/UVES (for high-z) and HST/COS (for low-z), to study their CGM using absorption line spectroscopy. An overview of the initial main results of these surveys will be presented in the talk. In particular, the dependence of the CGM properties on the SFR, stellar mass, impact parameter, and on redshift will be discussed.
Thursday Feb 21, 10:30
Ivo Labbe (Swinburne)
Colloquium: Galaxy Formation in the First Billion Years
Recent years have seen enormous progress in studies of galaxies
in the first billion years of the universe, during the epoch of
reionization. I will discuss state-of-the-art observations with
HST, Spitzer, ALMA, and ground-based facilities, focusing on
how they are used to identify, spectroscopically confirm, and
characterize the earliest star-forming and quiescent galaxies.
I will discuss evidence for ubiquitous strong nebular emission lines,
and implications for stellar mass build up and reionization of the
intergalactic medium. Finally, I will describe preparations
expectations for next-generation facilities such as the James Webb
Space Telescope.
Thursday Feb 14, 10:30
Sebastiano Cantalupo (ETH Zurich)
Colloquium: Illuminating the Cosmic Web with Fluorescent Ly-alpha emission
Our standard cosmological model predicts that most of the matter in the universe is distributed into a network of filaments - the Cosmic Web - in which galaxies form and evolve. Because most of this material is too diffuse to form stars, its direct imaging has remained elusive for several decades leaving fundamental questions about the structure of the universe still open, including: How are galaxies linked to each other? What are the morphological and physical properties of the Cosmic Web on both large and small scales? How do galaxies accrete gas from the Cosmic Web? In this talk, I will tackle these questions using the results of a new program to directly detect and study high-redshift cosmic gas in emission using bright quasars and galaxies as external "sources of illumination". In particular, I will show results from ultra-deep narrow-band imaging and integral-field-spectroscopy with both MUSE/VLT and the Keck Cosmic Web Imager (KCWI) that revealed numerous giant Lyman-alpha emitting filaments extending up to several hundred kpc around quasars and bright galaxies. I will discuss how the unexpectedly high luminosities of these systems, together with the constraints from Helium and metal extended emission, represent a challenge for our current understanding of cosmological structure formation. In particular, I will show that current observations suggest that intergalactic gas around high-redshift galaxies and quasars has a much broader density distribution of cold material than expected from cosmological simulations and I will present our first attempts to understand the origin and nature of these structures using high-resolution hydrodynamical models. At the same time, current galaxy formation models lack an efficient mechanism to prevent too much intergalactic gas cooling onto galaxies at later epochs and rely on very strong "ejective" feedback. In the final part of the talk (if time allows), I will show how the interaction between high-energy radiation from star-forming galaxies and the gas surrounding them provides a natural way to prevent "excessive" intergalactic gas cooling onto galaxies and I will discuss HST/COS observations that provide support for the importance of this effect.
Thursday Feb 7, 14:00
()
Student Review: Wael Farah's 30-month review
Thursday Feb 7, 10:30
Melanie Kaasinen (MPIA)
Colloquium: Weighing the Molecular Gas Reservoirs of High Redshift Galaxies
One of the outstanding problems in galaxy evolution studies is to link
the evolution of the star formation rate of galaxies to their molecular
gas content. Observationally, the last decade of studies have led to a
clear picture of the cosmic star formation history, which peaked at z~2
and has declined since then. However, it is unclear whether the
declining star formation rates are simply the result of lower molecular
gas masses, or whether the star formation efficiency has also evolved.
In this talk, I will discuss how the molecular gas contents of galaxies
are measured and highlight the difficulties of doing so at high
redshift. I will describe one of the most popular approaches, which
relies upon the dust continuum emission, and will present our recent
work where we test the validity of the dust continuum calibration
via a unique sample of z~2 galaxies with observations of both dust
continuum and CO(1-0) line emission.
Thursday Jan 31, 10:30
Mattheu Schaller (Leiden Observatory)
Colloquium: Baryonic effects on next-generation cosmological probes - How will we get the accuracy required?
In recent years cosmological hydro-dynamical simulations of representative volumes have reached a level of maturity where they
can be compared effectively against observational data. They can also be used to shed some lights onto galaxy formation processes
and how they affect the distribution of baryonic and dark matter. Understanding these effects is a key element required to fully
unlock the science of the next generation cosmological probes such as the Euclid mission.
In this talk, I will review some results from the EAGLE set of cosmological simulations focusing on the aspects highlighted above. I
will then discuss the challenges that lay ahead in terms of simulation complexity and how we are tackling some of them using our
new modern and open-source simulation code SWIFT.
Thursday Jan 17, 10:30
Xavier Prochaska ()
Colloquium: The Wolfe Disk: ALMA Discoveries of Distant, HI-selected Galaxies
I will review our series of successful programs to dissect the interstellar medium of distant, star-forming galaxies with the Atacama Large Millimeter Array (ALMA). In particular, I will discuss surveys of the set of HI-selected galaxies known as the damped Lya systems (DLAs). We resolve, in part, a decades-old struggle to identify the galactic counterparts of these DLAs and thereby place them firmly in the modern picture of galaxy formation. I will also highlight high spectral and spatial resolution observations of the Wolfe Disk, a z~4 galaxy with a Milky Way-like rotation curve.