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Colloquia Series

For more information on colloquia at the Centre for Astrophysics and Supercomputing please contact Dr. Nikole Nielsen ()

Swinburne Virtual Reality Theatre
AR Building, Room 104
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2011 Colloquia

Tuesday Dec 20, 11:30
Caroline Foster (ESO)
Colloquium: Multiplexing Multi-object Spectrographs for an integral view of nearby galaxies
Abstract: I describe some of the techniques I've used and helped develop during my PhD at Swinburne to infer the global properties of nearby galaxies and their globular cluster systems. The most salient results and their potential significance for galaxy and globular cluster formation are presented.
Thursday Dec 15, 11:30
Nicola Napolitano (Napoles)
Colloquium: Mass distribution of elliptical galaxies with Planetary Nebulae
Abstract: Planetary Nebulae (PNe) are good tracers of the stellar kinematics of elliptical galaxies out to ~5-10 effective radii and able to provide a detailed view of the 2D galaxy velocity field for these systems. If combined with long-slit spectroscopy of central galaxy regions, PNe allow us to model the mass distribution of ellipticals and constrain their dark halo properties. I will present the latest results of the galaxy kinematical mapping and mass modelling of a sample of elliptical galaxies observed with the Planetary Nebula Spectrograph, the first custom-designed instrument for counter-dispersed imaging which is optimized for PN radial velocity measurements. In particular, I will show that elliptical galaxies have dark matter halos that seem to be fairly consistent with expectations of cosmological simulations in the LCDM cosmology.
Thursday Dec 8, 14:00
Nick Kaiser (IfA, Hawaii)
Colloquium: The Pan-STARRS Wide-Field Imaging Survey
The Pan-STARRS PS1 telescope has been fully operational and surveying the sky for approximately 1.5 years. It will shortly be joined by the second telescope PS2. The PS1+2 system will be the world's most powerful wide-field survey instrument. In this talk I shall describe the Pan-STARRS design and review the performance of PS1; highlight some early science results; and describe the plans for operation of PS1+2 and the synergies that this will allow with other up-coming missions
such as Euclid and eRosita and other ground-based surveys.
Tuesday Dec 6, 11:30
Bililign Dullo ()
Student Review: Bililign Dullo 18-month review
Thursday Dec 1, 11:30
Amanda Bauer (AAO)
Colloquium: Linking Star Formation Histories with the Growth of Stellar Mass
Abstract: As surveys of galaxy populations at high redshifts progress, it becomes increasingly urgent to understand how observed galaxies at high redshift map into those at lower redshift. In this talk, I investigate how and where stellar mass builds up over cosmic time by showing recent studies of the changing star-forming properties of galaxies as a function of stellar mass and environment from redshift three to present.
Tuesday Nov 29, 11:30
Stefan Oslowski ()
Student Review: Stefan Oslowski's 30-month review
Friday Nov 25, 14:30
S. R. Kulkarni (California Institute of Technology)
Colloquium: The Restless Universe (Palomar Transient Factory)
Cosmic explosions were first noted nearly two thousand years ago.
However, secure recognition and study began only a hundred years
ago. What was once termed as Stella Nova (new stars) are now divided
into two major families, novae and supernovae (with real distinct
classes in each). Equally the variable stars have a rich phenomenology.
Together, supernovae and variable stars have contributed richly to
key problems in modern astrophysics: distances to galaxies, cosmography
and build up of elements in the Universe.

The Palomar Transient Factory (PTF), an innovative 2-telescope
system, was designed to explicitly to chart the transient sky with
a particular focus on events which lie in the nova-supernova gap.
PTF is now finding an extragalactic transient every 20 minutes and
a Galactic (strong) variable every 10 minutes. The results so far:
identification of an emerging class of ultra-luminous supernovae,
the earliest discovery of a Ia supernovae, discovery luminous red
novae, the most comprehensive UV spectroscopy of Ia supernovae,
discovery low energy budget supernovae, clarification of sub-classes
of core collapse and thermo-nuclear explosions, mapping of the
systematics of core collapse supernovae, identification of a trove
of eclipsing binaries and the curious AM CVns.
Friday Nov 25, 11:30
Christina Blom ()
Student Review: Christina Blom's 30-month PhD review
Thursday Nov 24, 11:30
Orsola De Marco (Macquarie University)
Colloquium: How common envelope binary interactions change the life of stars and planets
An expanding giant star may engulf a nearby stellar or substellar companion. The common envelope phase that follows, fundamentally alters the evolution of both stars in the system by reducing the orbital separation and leading to a merger (such as V838 Mon or V1309 Sco), or a compact binary (e.g., novae, type Ia supernova progenitors, X-ray binaries). Frequencies and physical properties of all compact, evolved binaries depend sensitively on the poorly understood common envelope phase. We have developed 3- dimensional, hydrodynamic common envelope simulations between a red giant branch star and a range of companions. Comparing the modelled ejected masses and final separations with observations, we revisit our understanding of the common envelope efficiency, a parameter on which predictions such as supernova type Ia rates sensitively rest. Finally, we bring our results to bear on the surprising result that some planets can survive a common envelope phase with their mother star.
Thursday Nov 17, 11:30
Jill Rathborne (CSIRO)
Colloquium: Brewing Great Science with MALT90
Abstract: The Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey is a new, international project aimed at characterizing the physical and chemical evolution of high-mass star-forming cores. Exploiting the unique broad frequency range and fast-mapping capabilities of the Mopra 22-m Telescope, MALT90 will obtain 3′×3′ maps toward ~3000 point sources identified in the ATLASGAL 870 μm galactic plane survey. Because we can map 16 lines simultaneously with excellent spatial (38′′) and spectral (0.11km s−1) resolution, the data reveal a wealth of information about source morphologies, chemistry, and kinematics. In this talk I will outline the survey strategy, current status, showcase some early results, and discuss several exciting follow-up projects we have planned with ALMA.
Friday Nov 11, 11:30
Tamas Budavari (JHU)
Colloquium: Streaming Analysis for the Largest Data
Focusing on scalability and applicability to the largest datasets, I will present streaming strategies. This class of approximate methods are often the only hope to analyze the upcoming surveys, such as the SKA or the LSST. After a brief introduction, I will talk about the ever-so-popular Principal Component Analysis (PCA), which is the swiss-army knife of many data scientists. The methodology is generalized to introduce robustness against outliers in the statistical sense without significant computational overhead. The performance is illustrated on real astronomy measurements and synthetic streams. Time permitting we will also discuss ongoing project on streaming image analysis and blind deconvolution.
Thursday Nov 10, 11:30
Gavin Rowell (Adelaide)
Colloquium: TeV Gamma-Rays: A new Window onto the High Energy Universe
TeV gamma-ray astronomy has progressed rapidly the past half-decade to being one of the highest impact astronomical disciplines today. TeV gamma-rays are a highly effective probe of nature's particle accelerators such as supernova remnants, pulsars, black holes and massive stars and their formation regions. Results are having impact on big questions like the origin of cosmic-rays and electrons, properties of magnetic fields, our understanding of relativistic flows, massive stellar evolution, interstellar gas, and constraints on dark matter properties. Many puzzles remain however, including the fact that over 30% of TeV sources in the Milky Way are unidentified. In this talk I will outline some of the Adelaide-led research activities in this field and highlight the intimate links with radio and X-ray astronomy. The talk will conclude with a look at future directions in TeV gamma-ray astronomy and its projected impact.
Thursday Nov 3, 11:30
Max Bernyk ()
Student Review: Max Bernyk 18 Month Review
Wednesday Nov 2, 11:30
Felix J. Lockman (NRAO)
Colloquium: (NOTE SPECIAL DATE) Making the Milky Way -- The Continuing Story
Abstract: The first part of the talk is about the Green Bank 100-meter diameter radio telescope, its dramatic origin and unique capabilities, and some of its recent scientific programs including the search for gravitational radiation, Mercury's molten core, organic
chemistry in interstellar space, and the growth and evolution of galaxies.

The second part of the talk will expand on the topic of the evolution of galaxies, with a focus on the Milky Way's need for continual growth through the addition of fresh material. Recently we have discovered that there is a large gas cloud in the process of merging with the Milky Way. This unique object holds information on the evolution of the Galaxy, the structure of the
gaseous halo, and the existence of dark matter halos.
Thursday Oct 27, 11:30
Eyal Kazin (Swinburne)
Colloquium: Testing Cosmology and Gravity with the Large Scale Structure
Testing Cosmology and Gravity with the Large Scale Structure

Galaxy clustering measurements play an essential role in constraining cosmology. Here I present new clustering results obtained from the WiggleZ Dark Energy Survey blue-line emission galaxies (z<1) and the Sloan Digital Sky Survey (SDSS) luminous red galaxies (z<0.5).
Combining SDSS and WiggleZ data sets we detect a significant baryonic acoustic feature (~5sigma), a relic from early Universe plasma waves that left ripples in the distribution of matter. This 140 Mpc signature is a cosmic standard ruler with which we test the
geometry of the Universe and constrain parameters of the standard LCDM model.
(For more details see:

I also present preliminary results of a test of gravity on large-scales (50-110 Mpc), when using anisotropies in galaxy clustering measurements of the SDSS sample. Doppler shift measurements are strongly contaminated by degeneracies between the Hubble expansion and peculiar velocities causing apparent anisotropies in redshift maps. Because these ``redshift distortions" are sensitive to the galaxies' dynamical environment, they can ultimately
be used to test General Relativity and alternative models. One difficulty in these measurements is measuring the galaxy "bias" (meaning the clustering amplitude ratio between dark matter and its tracers) of the sample due to degeneracies.In these results I show that this can be overcome with the use of the Halo Occupation Distribution framework, which uses real-space clustering to quantify how galaxies are distributed within dark matter halos.
Tuesday Oct 25, 11:30
Guido Loloya (Swinburne)
Student Review: Guido Loloya 6-month PhD review
Thursday Oct 20, 11:30
Tyler Bourke (Harvard)
Colloquium: New Insights into Low Mass Star Formation
Recent and ongoing observational and theoretical work is providing new insights into low-mass star-formation in the Galaxy. In particular, surveys of nearby molecular clouds with the Spitzer Space Telescope, combined with surveys at other wavelengths, have provided strong observational constraints on the luminosity and evolutionary status for a large ensemble of young stars. Armed with this information, details of the low-mass star formation paradigm are being revealed for the first time, such as lifetimes, accretion evolution, and very low mass star formation. This talk will present some of these new results and discuss how they are informing our view of low-mass star formation.
Tuesday Oct 18, 11:00
Amr Hassan (Swinburne)
Student Review: 30 Month Ph.D review
Thursday Oct 13, 11:30
Peter Jensen (SUT)
Student Review: 30 mo PhD talk
Dynamically-Driven Galaxy Evolution in Cold Front Clusters
Tuesday Oct 11, 11:30
Felix Lockman (NRAO)
Colloquium: TBA - SPECIAL DATE
Abstract TBA
Tuesday Oct 11, 11:30
Georgios Vernados (Swinburne)
Student Review: Georgios Vernardos 6-month PhD review
Friday Oct 7, 11:30
Peter Barnes (Florida)
Colloquium: *NOTE SPECIAL DATE* Large-Scale Surveys of Star Formation in the Milky Way
The formation of massive stars and star clusters is still poorly understood, despite its importance in cosmology, ecology of the ISM, and stellar demographics. We still debate such basic questions as the main formation mechanism and the timescales. However, a wealth of data from several new surveys promises to transform our understanding of this process.

I will present background and new results from two large-scale surveys of molecular gas and star formation content of the Milky Way's 4th quadrant. CHaMP is a multi-wavelength, sensitive, unbiased, and uniform study of all massive star formation sites at sub-parsec resolution within a 20x6 degree window in Vela, Carina, & Centaurus, including both the cold molecular gas and warmer areas heated by embedded young star clusters. The CHaMP clouds show a range of unexpected but key properties that shed new light on molecular cloud evolution and star cluster formation. ThrUMMS completely maps the remaining 60x2 portion of the 4th quadrant in 12CO, 13CO, C18O, and CN at arcminute- (ie, parsec-scale) resolution, and will be a key tool for obtaining distances to structures revealed by Hi-GAL, GLIMPSE, and many other surveys, as well as characterising the physics of GMCs in more detail than possible previously. Both surveys feature freely downloadable image & data files for custom analysis and other applications.
Tuesday Oct 4, 14:00
Vincenzo Pota (CAS / FICT / SUT)
Student Review: A survey of GC kinematics in early-type galaxies
18 month PhD talk
Tuesday Oct 4, 11:30
David Silva (NOAO)
Colloquium: SPECIAL SEMINAR - NOAO: Today and Tomorrow
The National Optical Astronomy Observatory (NOAO) is the US national
research and development center for ground-based, night-time,
optical-infrared astronomy. Its core mission is to provide access for
all qualified professional researchers, via peer review, to
state-of-the-art scientific capabilities. Through that access, the US
research community is investigating a broad range of modern
astrophysical problems from small bodies within our own Solar System, to
the most distant galaxies in the early universe, to indirect
observations of dark energy and dark matter. To support that mission and
help further US leadership in the international arena, NOAO is leading
the development of the US Optical/Infrared (O/IR) System ‚ the ensemble
of Federal and non-Federal observatories dedicated to international
leadership in scientific research, technical innovation, education, and
public outreach. NOAO is also leading programs that help enable a new
generation of telescopes, instruments, and software tools to meet the
research challenges of the next decade. In particular, NOAO is deeply
involved in the development of Dark Energy Survey (DES), Big Baryon
Oscillation Spectroscopic Survey (BigBOSS), and Large Synoptic Survey
Telescope (LSST). This talk will survey the state of NOAO today as well
as our plans for the next 10 years.
Thursday Sep 29, 11:30
Raquel Salmeron (ANU)
Colloquium: Structure and dynamics of wind-driving protostellar disks
Abstract: A surprising feature of many of protostellar accreting systems is their association with powerful outflows of material, which become highly collimated and supersonic as they accelerate away from the source. Their ubiquity suggests that there must be an underlying physical link between the inflowing disk matter and the outflowing wind. Magnetic fields that couple to the gas are thought to power the jets by removing angular momentum from disk matter, enabling it to accrete. These jets are, therefore, central to the dynamics and evolution of these systems, and to the overall process of star and planet formation. In my talk I will examine the properties and launching of outflows from the surfaces of protostellar disks under realistic fluid conditions, as well as their relation to magnetically-driven turbulence via the magnetorotational instability (MRI). I will present new models that calculate the dynamical and thermal structure of the disk and wind, and discuss their application for the analysis of observational data from young stars. I will also present models for the processing of dust particles in wind-driving protostellar disks, the analogues of the early solar system. Our models suggest that these powerful jets may be suitable sites for the formation of chondrules, the primitive, thermally-processed constituents of meteorites whose origin in the cold environment of the early solar nebula has remained elusive for many decades.
Tuesday Sep 27, 11:30
Sreeja Kartha (Swinburne)
Student Review: Sreeja Kartha 6-month PhD review
Friday Sep 23, 11:30
Helga Denes ()
Student Review: Helga Denes 6 month review (to be confirmed)
Thursday Sep 22, 11:30
Kathrin Wolfinger ()
Student Review: Kathrin Wolfinger 18 month review (to be confirmed)
Thursday Sep 15, 11:30
Duncan Galloway (Monash)
Colloquium: Probing dense matter in neutron stars via thermonuclear bursts
Abstract: Substantial uncertainty remains about the properties of matter at and above densities
reached in the atomic nucleus. This uncertainty can largely be attributed to the inaccessibility of such conditions to laboratory-based experiments. Neutron stars, the dense remnants of supernova explosions in medium-sized stars, serve as (rather remote and inaccessible) "laboratories" in which to investigate this regime. In particular, space-based X-ray observations of thermonuclear bursts in neutron stars can lead to measurements of neutron star spin, as well as (in principle) constraints on the neutron star mass and radius, sufficient to constrain the (highly uncertain) equation of state. I will present a brief summary of current research in this area as well as some new results and outstanding issues which must be addressed.
Thursday Sep 8, 11:30
Narae Hwang (National Astronomical Observatory of Japan)
Colloquium: Extended Star Clusters and Galaxy Evolution
Extended Star Clusters (ESCs) are a family of star cluster populations characterized by their large size compared to typical globular clusters (GCs). During the last decade, we have witnessed a large jump in the number of ESCs discovered in the local universe (e.g., NGC 6822, M31, M33, M51, etc.). This provides an ideal opportunity to explore what ESCs can tell us about the evolution of their host galaxies through observational and theoretical studies.

I am going to summarize the current status of observational studies on ESCs and to discuss their possible usage as a tracer of galaxy evolution processes implied by several theoretical studies.
Thursday Sep 1, 11:30
Tamás Budavári (John Hopkins)
Colloquium: Data-Intensive Astronomy
The way we do science changes rapidly. In the era of surveys, the statistical and computational challenges are more prominent than ever. We will discuss some of the fundamental issues that are at the core of most astronomy studies. A powerful Bayesian approach is introduced for cross-identifying sources, which is extendable, e.g., to incorporate models of spectral energy distributions, to accommodate the proper motion of stars, and to match transient events in space and time. As extreme computing becomes part of mainstream science for tackling the Big Data problems of both observations and simulations, we have to re-evalute our methodology. We will look at promising incremental approaches and GPU-based solutions to both analyses and visualizations.
Thursday Aug 25, 11:30
Jeff Cooke (Swinburne)
Colloquium: Ultraviolet-luminous supernova detections at z > 2 and their host galaxies
I will discuss our galaxy monitoring method that has successfully detected 12 supernovae
at z > 2 in the Canada-France-Hawaii Telescope Legacy Survey Deep fields. I will present
supernova light curves and late-time Keck spectra which includes two recently discovered
ultra-luminous, pair-instability supernova (PISN) candidates at z=2.045 and z = 3.887.
Because our supernova program monitors z > 2 Lyman break galaxies (LBGs), I will compare
the rest-frame ultraviolet photometric and spectroscopic properties of the supernova host
galaxies with respect to the complete (~100,000) LBG sample and discuss observed trends
and implications. Upcoming LSST and Hyper-SuprimeCam surveys are poised to detect
~50,000 supernovae at z ~ 2 - 6 that will fully characterize these events and enable tight
constraints on their progenitors and, potentially, the form of the high-redshift IMF. Finally,
because Population III stars are believed to result in PISNe, detection of ultra-luminous PISN
candidates at high redshift similar to those presented here, offers our best means to provide
observational examples of the deaths of the first stars.
Tuesday Aug 23, 11:30
Chris Usher (CAS)
Student Review: The halo metallicities of early-type galaxies
18 month PhD talk
Tuesday Aug 16, 11:30
C.Gonzalo Diaz (Swinburne)
Student Review: 18 Month Ph.D Review
Thursday Aug 11, 10:00
Mal Bryce (Curtin University)
Colloquium: The National Broadband Network
Mal Bryce is the former Deputy Premier of Western Australia, an Adjunct Professor of Curtin University, and Chairman of the Pawsey Centre project in WA to establish world-class super-computing facilities as part of the preparation for the bid for the Square Kilometer Array Telescope. He was founding Chairman of the Australian Centre for Innovation.

For most of his working life, Mal has been engaged in developing companies, communities and public policy to harness the power of new technology. Throughout the 1990s he was a leading Australian pioneer in the development of the Internet industry and the application of the Internet to business, government agencies and communities. He was the architect of Australia’s first online community in Ipswich and he led the team that implemented one of Australia’s first e-Commerce Projects.

Professor Mal Bryce will give a presentation to FICT Staff on NBN. The details are:

DATE: Thursday, 11th August

TIME: 10.00am - 11.00am

Thursday Aug 11, 11:30
Stuart Wyithe (Melbourne)
Colloquium: The Epoch of Reionization
Over the last decade observational cosmology has matured to the point where quantities such as the mass, composition, and age of the Universe are now measured with a precision of a few percent. In contrast, the formation of the highest redshift galaxies and their role in the reionization of the IGM remains very poorly understood. I will review the constraints that may currently be placed on reionisation from existing observations of high redshift galaxies and quasars. I will then describe the new era for the study of high redshift galaxies that will open following the construction of the next generation of low-frequency radio-telescopes, including LOFAR and the MWA. These telescopes will enable reionization to be studied directly, using tomography of the 21cm line to measure the distribution of neutral hydrogen. I will discuss some of the associated observables, including quasar HII regions and the power-spectrum of intensity fluctuations.

Tuesday Aug 9, 11:30
Pierluigi Cerulo (CAS)
Student Review: The build up of the red sequence in high redshift galaxy clusters
6 month PhD talk
Thursday Aug 4, 11:30
Matthew Graham (Caltech)
Colloquium: Smart astronomy: tackling the challenges of the time domain
Abstract: The next generation of sky surveys will produce unprecedented volumes of high dimensional complex data. This is both a boon for scientific discovery and a bane because of the technical difficulties it presents. In particular, dealing with the heterogeneous collections of past detections, contextual information and general annotations associated with real-time event streams is a major challenge. Moore's law alone is insufficient to solve this; rather it requires a smarter approach incorporating domain knowledge into computational processes. In this talk, we will discuss how semantic technologies can be applied to achieve this and show how qualitative information can be represented in a quantitative fashion, allowing it to be employed in data mining algorithms, such as object classifiers or clustering methods, and visualizations. Furthermore we will demonstrate how data visualization is a key aspect of this process, providing a unique handle to determining the relative importance of different pieces of information, and how citizen science projects are being developed to understand this.
Tuesday Aug 2, 11:30
Evelyn Caris (Swinburne)
Student Review: 30 month PhD review: Evolution of sizes and velocity dispersions of red galaxies
Supervisors: Karl Glazebrook, Lee Spitler
Thursday Jul 28, 11:30
Richard Wilman (Swinburne)
Colloquium: Probing cold feedback in cluster cores with IFU spectroscopy
There is now abundant evidence for the existence of multiphase cool gas, dust and star formation in the cores of some rich clusters of galaxies in the local universe. Here I will present integral field spectroscopy of the ionized (HII) and molecular (hot H2) line emission in several such systems; I will describe how they appear to be captured at distinct stages of the cold feedback cycle of Pizzolato & Soker, in which the central radio-loud AGN are fuelled by cooled molecular gas (as opposed to Bondi accretion of hot gas). In many cases, direct links can now be established between the cooling X-ray ICM, infalling filaments of molecular gas at radii 1-10 kpc and the transition to nuclear disks of hot H2 at r<100 pc. With adaptive optics, such disks can be used for dynamical mass measurements of the central supermassive black hole, placing further constraints on the energetic viability of AGN feedback.
Thursday Jul 21, 11:30
Mike Dopita (Australian National University)
Colloquium: Re-ionizing the Universe without Stars (?)
Abstract: Recent observations show that the measured rates of star formation in the early universe are insufficient to produce re-ionization, and therefore, another source of ionizing photons is required. In this talk I examine the possibility that these can be supplied by the fast accretion shocks formed around the cores of the most massive haloes (10.5 < logM/M⊙ < 12)
on spatial scales of order 1 kpc. We model the detailed physics of these fast accretion shocks, and apply these to a simple 1-D spherical hydrodynamic accretion model for baryonic infall in dark matter halos with an Einasto density distribution. The escape of UV photons from these halos is delayed by the time taken to reach the critical accretion shock velocity for escape of
UV photons; 220 km s−1, and by the time it takes for these photons to ionize the surrounding baryonic matter in the accretion flow. Assuming that in the universe at large the baryonic matter tracks the dark matter, we can estimate the epoch of re-ionization in the case that
accretion shocks act alone as the source of UV photons. We find that 50% of the volume (and 5% of the mass) of the universe can be ionized by z ∼ 7 − 8. The UV production rate has an uncertainty of a factor of about 5 due to uncertainties in the cosmological parameters controlling the development of large scale structure. Because our mechanism is a steeply rising
function of decreasing redshift, this uncertainty translates to a re-ionization redshift uncertainty of less than 0.5. We also find that, even without including the UV photon production of stars, re-ionization is essentially complete by z ∼ 5.8. Thus, fast accretion shocks
can provide an important additional source of ionizing photons in the early universe.
Friday Jul 15, 11:30
Duncan Galloway (Monash)
Colloquium: TBA
Abstract: TBA
Tuesday Jul 12, 11:30
Ben Barsdell (Swinburne)
Student Review: 30 Month Ph.D review
Friday Jul 1, 11:30
Dennis Crabtree (HIA - Canada)
Colloquium: ngCFHT - A 10-m Dedicated Wide-Field Spectroscopic Facility
Abstract: The science case for a wide-field spectroscopic capability on an 8-m class telescope, initially put forward in the KAOS Purple Book,is stronger than ever.A virtual explosion of wide-field imaging surveys in the coming decade (VST, Pan-STARRS, Skymapper, HSC, LSST, DEC, VISTA, and others), as well as the launch of GAIA, will demand efficient spectroscopy to maximize their science impact.

We have recently proposed upgrading the CFHT to a 10-m segmented mirror facility dedicated to wide-field, highly multiplexed spectroscopy (FOV 1.5 sq. degrees and, 800 or 3200 fibers depending on spectral resolution. ngCFHT will reuse much of the existing CFHT infrastructure and the CFHT partnership will be expanded to four or more partners. Both of these will reduce the cost of building and operating this facility for each participating country.

In this talk I will cover the science case for such as facility, the concept and technical specifications and the current status of the project.
Thursday Jun 30, 11:30
Holger Baumgardt (Queensland)
Colloquium: Intermediate-mass black holes in star clusters
The possible existence of intermediate-mass black holes (IMBHs) has received considerable attention in the literature in recent years. They might have formed in the early universe as progenitors to supermassive black holes, or formed later by the merging of several massive stars in the centers of dense star clusters. In the second scenario it is natural to expect that globular clusters and some compact open clusters could harbor central IMBHs. In my talk I will first give an overview of the observational signatures these IMBHs give rise to. I will then present results from a large search programme with HST and VLT/FLAMES looking for IMBHs in several galactic globular clusters.
Tuesday Jun 21, 11:30
Paul Coster (CAS / FICT / SUT)
Student Review: 6 mo PhD talk by Paul Coster
6 month PhD talk
Thursday Jun 16, 11:30
Paul Nulsen (Harvard-Smithsonian CfA)
Colloquium: Cygnus A: X-ray Perspective on a Powerful Radio Galaxy
Abstract: Cygnus A is the nearest powerful radio galaxy and it is hosted by the central galaxy of a massive cool core cluster. The X-ray image of Cygnus A reveals a great deal of structure, including cocoon shocks and X-ray jets that do not coincide with its radio jets.Implications of the X-ray data will be discussed. In particular, theyhave been used to estimate the mean jet power. X-ray emission from the jets is best explained by a synchrotron model. However, the synchrotron lifetimes of only ~200 yrs suggest that the X-ray jets rather than the radio jets are the main path of energy flow from the AGN to the hotspots. This has significant implications for models of the jets in Cygnus A.
Thursday Jun 2, 11:30
David Parkinson (Queensland)
Colloquium: Tests of Modified Gravity theories using Redshift-space distortion measurements from WiggleZ
The mysterious dark energy that drives the acceleration can be seen either as a failure of Einstein's theory of General Relativity, or the requirement of (yet another) dark fluid to reconcile the theory with observations. However, both explanations make similar or identical predictions for the distances as a function of redshift. In order to break this degeneracy new data is needed, such as measurements of the growth of structure on large scales by redshift-space distortions. WiggleZ has provided us with just such a data set to test these theories. I will describe the procedure for generating predictions for the different theories, the WiggleZ redshift-space distortion data set, and the constraints this data places on the different theories.
Thursday May 26, 11:30
Carlos Contreras (Swinburne)
Student Review: 30 Month Ph.D review
Thursday May 19, 11:00
Chiara Tonini (Swinburne)
Colloquium: The hierarchical build-up of the Tully-Fisher relation
We present the first comprehensive analysis of the evolution of the Tully-Fisher relation up to z~1 obtained with a semi-analytic model of galaxy formation, in a set of photometric bands from B to K. We employ the Maraston05 stellar population models, and a realistic treatment of galaxy rotation curves that takes into account the dynamical effects of bulge formation. We use the comparison with data across the 0<1 redshift range to investigate the merits and faults of galaxy assembly in the model, and the soundness of the recipe for disk formation as determined by the dark matter halo structure. We find that the model star formation rates decline too slowly with redshift, so that we cannot simultaneously reproduce the optical TF both at high and low redshift. The near-IR TF is instead better reproduced in the same redshift range, showing that the model mass assembly history is realistic. However, although the model is also able to produce a morphology dependence of the K-band TF in reasonable accord with the data, the hierarchical build-up of galaxies prevents the model from producing massive bulgeless spirals. We also find that the model disk scale-lengths are too large compared with observations, hinting to a dynamical interaction between the disk and the dark matter halo more complex than the angular momentum conservation scenario usually implemented in semi-analytic models.
Thursday May 12, 11:00
Joss Bland-Hawthorn (University of Sydney)
Colloquium: Reconstructing ancient star clusters in dwarf galaxies
The chemical abundance patterns of the oldest stars in the Galaxy are expected to contain residual signatures of the first stars in the early universe. Just how the complex data are to be interpreted with respect to "progenitor yields" remains an open question. Here we show that stochastic chemical evolution models to date have overlooked a crucial fact. Essentially all stars today are born in highly homogeneous star clusters and it is likely that this was also true at early times. When this ingredient is included, the overall scatter in the abundance plane can be much less than derived from earlier models. We present tentative evidence for the existence of a dissolved star cluster in the Sextans dwarf galaxy. We use the technique of chemical tagging to identify stars that are highly clustered in a multi-dimensional abundance space. If corroborated by follow-up spectroscopy, the star cluster at [Fe/H]=-2.7 is by far the most metal-poor system identified to date. In an era of extremely large telescopes, we anticipate that this will be a powerful technique for tracing the evolution of the cluster mass function in dwarf galaxies.
Thursday May 5, 11:00
John Peacock (University of Edinburgh)
Colloquium: Probing gravity with galaxy surveys
Modifications of gravity are studied with growing interest in cosmology. A strong motivation comes from the puzzling existence of dark energy; since the existence of DE is only inferred from the Friedmann equation, it may be that DE does not exist, but that a different equation should apply. A way to tell is to look for evidence of non-standard gravity on smaller scales, via the growth of large-scale structure. This can be measured via the Integrated Sachs-Wolfe effect and via redshift-space distortions of clustering. This talk shows estimates of the ISW effect and their impact on the CMB data. It also presents new measurements or redshift-space clustering using 160,000 redshifts from the GAMA survey. At the 10% level, the results from 6 different galaxy subsets are all consistent with the standard LCDM model. Future projects offering improved accuracy will be reviewed.
Thursday Apr 28, 11:00
Chris Power (ICRAR)
Colloquium: AGN feeding and feedback: a "first principles" approach
There are good astrophysical reasons to believe that AGN feedback must play a fundamental role in the formation of galaxies. As yet, however, our understanding of the physics of AGN/SMBH feeding and feedback can be described as qualitative at best. In this talk I will present key results from recent analytical and numerical work modelling AGN feeding and feedback. In particular I will discuss how physical properties of the large scale accretion flow impact on SMBH growth; the competition between SMBH growth and star formation; and the precise roles SMBH and stellar feedback in shaping the M-sigma and M?Mbulge relations.
Thursday Apr 21, 11:00
Ivy Wong (CSIRO Astronomy & Space Science)
Colloquium: Understanding the evolving Local Universe from a neutral gas perspective
The Local Universe provides an excellent high-resolution laboratory for studying the detailed processes of star formation and galaxy evolution. In this seminar, I will present some highlights from my multiwavelength studies of nearby galaxies selected from HIPASS, the largest neutral Hydrogen (HI) survey to-date. I will show that: (i) selecting galaxies via their HI content is a good way of selecting a large variety of star-forming galaxies regardless of size/stellar luminosity; (ii) the upper mass end of the stellar IMF may not be uniform; (iii) nearby post-starburst galaxies occupy the low-mass end of the green valley and represent a population of galaxies which are quickly going from the blue cloud to the red sequence; and (iv) unlike strong gravitational interactions, ram pressure does not strongly induce star formation.
Thursday Apr 14, 11:00
Chris Flynn (Uni. Turku)
Colloquium: A Schmidt-Kennicutt Law for Star Formation in the Milky Way Disk
We use a new method to trace backward the star formation history of the Milky Way disk, using a sample of M dwarfs in the solar neighborhood. M stars are used because they show H-alpha emission until a particular age, which is a well-calibrated function of their absolute magnitudes, allowing us to reconstruct the rate at which disk stars have been born over about half the disk's lifetime. Our star formation rate agrees well with those obtained by using other independent methods and seems to rule out a constant SFR. The principal result of this study is to show that a relation of the Schmidt-Kennicut type (which relates the SFR to the interstellar gas content of galaxy disks) has pertained in the Milky Way disk during the last 5 Gyr.
Thursday Apr 7, 11:00
Chiara Tonini (Swinburne)
Colloquium: The hierarchical build-up of the Tully-Fisher relation
We present the first comprehensive analysis of the evolution of the Tully-Fisher relation up to z~1 obtained with a semi-analytic model of galaxy formation, in a set of photometric bands from B to K. We employ the Maraston05 stellar population models, and a realistic treatment of galaxy rotation curves that takes into account the dynamical effects of bulge formation. We use the comparison with data across the 0<1 redshift range to investigate the merits and faults of galaxy assembly in the model, and the soundness of the recipe for disk formation as determined by the dark matter halo structure. We find that the model star formation rates decline too slowly with redshift, so that we cannot simultaneously reproduce the optical TF both at high and low redshift. The near-IR TF is instead better reproduced in the same redshift range, showing that the model mass assembly history is realistic. However, although the model is also able to produce a morphology dependence of the K-band TF in reasonable accord with the data, the hierarchical build-up of galaxies prevents the model from producing massive bulgeless spirals. We also find that the model disk scale-lengths are too large compared with observations, hinting to a dynamical interaction between the disk and the dark matter halo more complex than the angular momentum conservation scenario usually implemented in semi-analytic models
Thursday Mar 31, 11:00
Chris Tinney (UNSW)
Colloquium: New Planets from the Anglo-Australian Planet Search and New Prospects for Planet Searching
The Anglo-Australian Planet Search has been running on the AAT now for quite a number of years. Nonetheless it keeps finding new and interesting exoplanetary systems - like a "Neptune" in a 120d orbit, and a gas-giant in a 363d orbit. Planet searches world-wide are beginning to home in on the frequency of Earth-mass planets, which seem to orbit some 20% of stars .... albeit in Mercury-like orbits. The future for Doppler planet searches - even in the age of Kepler - remains incredibly fertile, and the AAPS is set to take advantage of some very exciting opportunities to implement new Doppler planet search technologies that have been developed right here in Australia.
Thursday Mar 24, 11:00
Jason Spyromilio (ESO)
Colloquium: The European Extremely Large Telescope Project
The E-ELT is the largest of the planned future optical/NIR ground based telescopes with a 42-m diameter primary mirror. The project has just concluded the detailed design phase (phase B). The presentation shall delve into the science drivers for the project and detail the current technical status, describe the level of industrial readiness in anticipation of a start of construction later this year.
Thursday Mar 17, 11:00
Ben Oppenheimer (Leiden University)
Colloquium: The Tale of Two Epochs: Galaxy Formation at z=6 and Today
The z=6 Universe appears nothing like the Universe today. The first galaxies are extremely blue, compact, and live in low-mass halos, while the intergalactic medium has a much higher neutral fraction and IGM metal enrichment appears to be in its earliest stages. By today, a diverse Hubble sequence of galaxies is in place, and metal absorption in quasar sight lines indicates the IGM is highly enriched with the nucleosyntheic products of star formation. We obviously have many more observations of the local Universe than at high-z; however, cosmological hydrodynamic simulations allow us to self-consistently evolve universes over 14 Gyrs, and understand the physical mechanisms driving the transfer of gas from the IGM into galaxies. I will briefly overview some results at z~6, focusing on the luminosity function of galaxies and the first metal absorbers observed in the spectra of the furthest discovered quasars. Then I will rapidly evolve one of our simulations in about a 20 second movie to z=0, and talk about both the present-day observed mass function of galaxies and the rich diversity of metal absorption lines being uncovered by the Cosmic Origins Spectrograph on Hubble. We have notable successes when making mock simulated observations directly comparable to observed data, but challenges and problems still exist. Ubiquitous star formation-driven superwinds at all epochs are the necessary and central ingredient to produce galaxies and an IGM like the ones we observe.
Thursday Mar 10, 11:00
Michael Brown (Monash University)
Colloquium: The ubiquitous radio emission from early-type galaxies
In the recent literature, a popular mechanism for regulating star formation in galaxies is AGN feedback, where an AGN injects sufficient energy into the gas within a galaxy to regulate star formation. Radio observations provide insights into the plausibility and nature of AGN feedback. For example, we may expect to observe radio emission from all galaxies, resulting from recent star formation or the AGNs that regulate star formation. We have studied the radio emission from K<9 early-type galaxies using VLA and single dish imagery. For the most massive galaxies, radio power spans four orders of magnitude and is strongly correlated with galaxy mass. All galaxies with a K-band absolute magnitude brighter than -25.5 have positive radio flux densities, and we thus conclude that all massive galaxies have recently undergone star formation or host an active galactic nucleus.
Thursday Feb 24, 11:00
Jonathan Gardner (NASA)
Colloquium: The James Webb Space Telescope
The James Webb Space Telescope is the successor to the Hubble and Spitzer Space Telescopes and is currently the largest science project in the United States. As a facility-class observatory, the scientific capabilities of Webb address almost all aspects of astronomy. Webb will find the first galaxies to form in the early Universe, decode the processes of star formation, take spectra of exoplanets and study the planets, moons and small bodies of the outer Solar System. Webb will be a large (6.6m) segmented, deployed, cold (50K) telescope launched to the second Earth-Sun Lagrange point. Webb will have four instruments: The Near-Infrared Camera, the Near-Infrared multi-object Spectrograph, and the Tunable Filter Imager will cover the wavelength range 0.6 to 5 microns, while the Mid-Infrared Instrument will do both imaging and spectroscopy from 5 to 28.5 microns. The Webb project is a partnership between NASA, ESA and CSA, who are supplying instrumentation and the launch vehicle. Webb will be operated by STScI in the same way as Hubble, with the majority of observing time available to astronomers worldwide through annual calls for proposals. Webb is currently under construction; the primary mirror segments and flight instruments are in their final stages of assembly, and the project will start the integration and testing phase soon. In this talk I will review the science and design of the observatory and describe recent progress in construction.
Thursday Feb 17, 11:00
Jessica Werk (UC Santa Cruz)
Colloquium: Metal Transport to the Gaseous Outskirts of Galaxies
Neutral hydrogen gas often extends far beyond the stellar component of galaxies in forms ranging from relatively quiescent extended disks to tidally stripped tails. Despite its ubiquity, knowledge of gas enrichment levels outside the stellar components of galaxies has remained somewhat limited. In this talk, I will describe a search for outlying HII regions in the gaseous outskirts of extended, disturbed, and/or interacting gas-rich galaxies, and subsequent Gemini Telescope multi-slit spectroscopy from which I obtain the nebular oxygen abundances of numerous outlying and centrally-located HII regions. Then, I will present oxygen abundance gradients out to 2.5 times the optical radius for 13 gas-rich galaxies that span a range of morphologies and masses. By analyzing the underlying stellar and neutral HI gas distributions in the vicinity of the HII regions, I attempt to identify the physical processes that could give rise to the observed metal distributions in galaxies. These measurements, for the first time, convincingly show flat abundance gradients at large radii in a wide variety of systems, and have important implications on the efficiency of metal transport in galaxies, the star-formation history of outer-disk material, and the potential expulsion of metals into the intergalactic medium.
Wednesday Feb 9, 11:00
Ralph Pudritz (McMaster University)
Colloquium: From Clouds to Star Clusters: Origins of the IMF
The origin of the Initial Mass Function (IMF) is arguably the most important problem of star formation. Despite the host of theoretical models have been created over the years to address this, the physics that converts interstellar gas possibly universal IMF is complex. Substantial observational progress is now being made by means of comprehensive and sensitive surveys of molecular cloud structure that measure the distribution functions characterizing the bulk properties of self-gravitating gas, star-forming cores, and filaments within molecular clouds. The origin of the IMF is known to be related to the formation of star clusters, and this talk will explore these connections. I shall focus on the progress that numerical simulations have made in the exploration of the physical processes that play a role in converting gas into star clusters. These include turbulence, self-gravity, cooling, magnetic fields, and dynamical interactions as stars emerge in cluster forming environments. Feedback processes including the termination of collapse by bipolar outflows and the suppression of fragmentation by radiative heating from massive young stars also play important roles. Taken together, a suggestive and interesting picture is beginning to emerge.
Friday Feb 4, 11:00
Ray Jayawardhana (Toronto)
Colloquium: Characterizing Exoplanets
On-going searches for extrasolar planets, despite certain limitations in sensitivity, have already revealed a remarkable diversity of worlds --from close-in super-Earths to far out super-Jupiters-- and challenged our preconceptions many times over. Meanwhile, comparative studies of exoplanet physical properties have begun in earnest: planets caught in transit and those imaged directly are best suited for detailed characterization, especially of their atmospheres. I will discuss recent results and future prospects, including the possibility of extending these techniques to lower-mass planets.