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Colloquia Series

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

Swinburne Virtual Reality Theatre
Applied Science Building, Room 406
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2006 Colloquia

December 20 @ 11:30
Richard Griffiths (Carnegie Mellon)
Title: Beyond the Deep X-ray Surveys: Galaxies or AGN?
The results from the deepest X-ray surveys will be briefly reviewed in the context of AGN and galaxy evolution.
Fluctuation analysis has shown that the number counts in the Chandra deep X-ray surveys are approximately 30,000 per sq. deg. at the fluctuation limit of 5 dex(-18) cgs in the soft (0.5 - 2 keV) band. These counts are greatly in excess of the predicted numbers of AGN at this flux level, based on extrapolations of our best models for the AGN luminosity function and its evolution. The number counts are similar, however, to the visible number counts of galaxies at B = 24 mag. and we have therefore used stacking analysis in order to detect them in the X-ray data. The stacking analysis has resulted in the detection of elliptical, spiral and irregular galaxies out to a redshift of 0.7, with average flux levels roughly consistent with those expected from B-band luminosities and L(X) / L(B) ratios at low redshift. But the observed X-ray evolution of spiral galaxies out to z = 0.7 is observed to be in excess of the expected value based on our best models for the evolution of the star formation rate and the anticipated evolution of the binary X-ray populations. The X-ray number counts can be explained by invoking AGN activity in some fraction of the spirals, e.g. AGN luminosity of 0.1 times the galaxy luminosity for 30% of the galaxies at z = 0.7.
The prospects for deep surveys using XEUS will be briefly summarised.
December 18 @ 15:00
Dragan Huterer (Chicago)
Title: Exploring the Dark Energy Domain
One of the great mysteries of modern cosmology is the origin and nature of dark energy - a smooth component that contributes about 70% of the total energy density in the universe and causes its accelerated expansion. I first discuss approaches to model and measure the expansion history of the universe in the presence of dark energy a variety of methods, from simple parametrizations to non-parametric methods. Then I comment on the importance of controlling the systematic errors in cosmological probes of dark energy, and show some examples from recent work on weak gravitational lensing systematics. Finally, I present results from a comprehensive study of a class of dark energy models, discussing current and expected future constraints, insights into the dynamics of dark energy, figures of merit, and a classification of theoretical models.
December 8 @ 11:30
David Bacon (Edinburgh)
Title: Progress in Cosmology with Gravitational Lensing
I will talk about my recent work showing how lensing is useful to examine substructure, dark energy and testing alternative theories of gravity.
December 7 @ 11:30
Alexander Knebe (Astrophysikalisches Institut Potsdam)
Title: Satellite Trek: Integral-space, the final frontier?
December 1 @ 11:30
Ed van den Heuvel (University of Amsterdam)
Title: Double Neutron Stars: Evidence for two different neutron star fomation mechanisms
Eight double neutron star systems are known in the galactic disk (and several more in globular clusters). The systems in the galactic disk are expected to be the products of the evolution of relatively massive interacting binary systems. While there is strong observational evidence that many neutron stars receive a kick velocity of order 400 km/s at birth, five of the eight double neutron stars in the galactic disk have remarkably low orbital eccentricities between about 0.08 and 0.25, indicating that second-born neutron stars in these systems received hardly any velocity kick at birth. The low-velocity second-born neutron stars tend to have rather low masses, between 1.18 and about 1.30 solar masses. It is argued that their characteristics are consistent with formation by the electron-capture collapse of a degenerate O-Ne-Mg core in stars which started out with masses between about 8 and 12 solar masses, while the high kick-velocity neutron stars most likely were formed by the collapse of the iron cores of stars which started out with masses above 12 solar masses. Possible reasons why these two different neutron-star formation mechanisms would produce different kick velocities will be discussed, as well as the implications of the low-velocity population for the understanding of the formation of low-mass X-ray binaries and globular cluster neutron stars.
November 29 @ 10:00 - 17:00
Title: CAS Sciencefest
November 14 @ 15:00
Joss Hawthorn (AAO)
Title: TBD
November 10 @ 11:00
Emil Lenc (Swinburne)
Title: Living Life on the Edge - High Resolution, Wide-field VLBI
November 9 @ 11:30
Harald Kuntschner (ESO)
Title: A new view of early type galaxies
Results from the SAURON survey are changing our view of the structure, dynamics and stellar populations in early type galaxies. I will report results on dynamical and population estimates of M/L and suggest a new physical classification of early type galaxies based on a measure of angular momentum. Then I will focus on the fossil record of the star-formation history as inferred from line-strength maps and up-to-date stellar population models. A significant fraction of galaxies in our sample show evidence of secondary star-formation and I will present results on the characteristics of these stellar populations and their dynamics.
October 26 @ 11:30
Ken Freeman (ANU)
Title: The Dynamical History of the Galaxy
I will discuss the dynamical history of the Galaxy, including its stellar halo, the first stars, the galactic bulge, disk heating, substructure and moving groups and the thick disk.
October 13 @ 11:30
Juergen Ott (ATNF)
Title: Ammonia in the Local (and not so Local) Universe
The transitions of ammonia, the most abundant top-heavy molecule, can be utilized as an easy-to-use thermometer for molecular gas. Over the last few years, a new generation of 1cm receivers at ATNF and other telescopes has been commissioned which enables astronomers to exploit this peculiar feature in far more objects than before. I will present results from extensive ammonia observations toward the Galactic Center, nearby starburst galaxies, and ULIRGS.
October 5 @ 11:30
Chris Fluke (Swinburne)
Title: Future Directions in Astronomy Visualisation
Every year, astronomers spend millions of dollars on telescopes, instruments and computers, yet they tend to look at the resulting data on small, flat, two-dimensional displays. Limiting factors seem to be the level of awareness of techniques that are available, and access to appropriate software tools to simplify the visualisation process. I aim to address both of these issues.
I will present a summary of our recent work on advanced image displays including stereoscopic projection and MirrorDome (full-dome digital projection on a budget). I will also demonstrate S2Plot: a new, 3-dimensional plotting library with support for both standard and advanced display devices. With a PGPlot-inspired interface, S2Plot provides astronomers with elegant techniques for displaying and exploring 3d data sets directly from their program code.
September 28 @ 11:30
Chris Blake (Swinburne)
Title: Cosmological measurements from galaxy surveys
I'll give a "big picture" introduction to the current main issues in cosmology, and the important role played by galaxy surveys in addressing these questions by mapping out the large-scale structure of the universe. In particular I'll show some cosmological measurements from a large photometric redshift catalogue of Luminous Red Galaxies in the Sloan Digital Sky Survey. I'll also explain how future surveys should be able to confirm or refute theories for the "dark energy".
September 14 @ 15:30
John Dickey (Tasmania)
Title: Structures in the Diffuse Interstellar Medium - From the Largest to the Smallest Scales
There are many tracers of small-scale structure in the neutral and ionized components of the diffuse interstellar medium. Some trace the gas density alone, or density combined with velocity, temperature, or the strength of a component of the magnetic field. Most of these are consistent with a power law structure function, strongly suggesting a turbulent cascade is at work in the ISM. But the physical processes that drive this turbulence, and that moderate the exchange of turbulent energy between the magnetic field, the ionized and neutral gas phases, and the cosmic rays, are not so well understood. Interstellar turbulence is ultimately tied to star formation, both because it is driven in part by stellar winds and supernova remnants, and because it shapes the structures from which new stars will form. But some tracers show that even where the star formation rate is very low, the turbulent properties of the diffuse medium are not very different from those nearby. The dynamical role of the magnetic field in the small scale structure of the diffuse medium has become particularly interesting in recent years, with many new observational results.
September 12 @ 11:30
Michael Drinkwater (UQueensland)
Title: Ultra-compact dwarf galaxies: a new component of galaxy clusters and groups
We recently reported the discovery of a new galaxy type, ultra-compact dwarf (UCD) galaxies, in both the Fornax and Virgo clusters. Here we present new detections of a larger population of faint UCDs in the Fornax Cluster, as well as the first detections of UCDs in a galaxy group. UCDs outnumber normal galaxies in the central region of the Fornax Cluster. We used this large UCD sample to test the tidal stripping model: simulations indicate that only about half of the UCD population may have formed by disruption of the observed population of nucleated dwarf galaxies. As the UCDs are strongly clustered towards the cluster centre, we conclude that the remaining UCDs must be associated with the much earlier assembly of the central galaxy.
September 7 @ 11:30
Jayaram Chenaglur (ATNF - On leave from NCRA/TIFR)
Title: HI in extremely faint dwarf galaxies
I will talk about Giant Metrewave Radio Telescope (GMRT) observations of HI in extremely faint dwarf galaxies. In hierarchical models of galaxy formation, the smallest galaxies form first and then merge to form larger galaxies. Nearby extreme dwarf galaxies are presumably those which have escaped this merger process. Detailed studies of these galaxies may hence provide insight into high redshift galaxy formation and evolution processes. Our GMRT observations cast light on a number of issues, including dark matter in the smallest gas rich galaxies, the impact of star formation on the gas and baryon content of these galaxies and the fine scale structure of their neutral ISM.
August 31 @ 11:30
Ramesh Bhat (Swinburne)
Title: ALFA Pulsar Survey: Progress and Highlights
The superb sensitivity of the Arecibo telescope and its new seven-pixel L-band feed array system (ALFA) allow us to conduct the deepest ever survey of pulsars in the Galactic plane. I will describe the background and motivation of this ongoing survey, strategies and sky coverage, and progress and highlights, including the discoveries of some interesting pulsars. The survey is anticipated to discover several hundreds of new pulsars within the Arecibo-visible part of the Galactic plane, and is especially sensitive to finding rapidly spinning millisecond pulsars, as well as those in compact binary systems. Prospects of the ALFA system to search for pulsars in external galaxies will also be briefly reviewed.
August 17 @ 11:30
Alastair Edge (University of Durham)
Title: TBD
August 10 @ 15:00
Sarah Maddison (Swinburne)
Title: Observing grain growth in protoplanetary disks
In order to understand planet formation, we need to probe the physical conditions of protoplanetary disks to see when and where grains begin to grow in size. Over the past four years we have been conducting a 3 mm continuum survey with ATCA of disks around young stars (both T Tauri and Herbig Ae/B stars) in southern molecular clouds to investigate the evolution of protoplanetary disks and grain growth within these disks. The goals of our project are to obtain fluxes and hence determine the millimetre spectral energy indices, which provides information about the grain size distribution. We present results from our successful 2005 millimetre season, in which we observed 15 southern T Tauri sources (10 in Chamaeleon and 5 in Lupus), obtaining 3sigma fluxes for ten sources and strict upper limits for the remaining five sources. The opacity indices suggest the presence of mm-sized dust aggr egates and hence substantial grain growth in the majority of these disks.
July 27 @ 11:30
Stuart Wyithe (Melbourne)
Title: Suppression of Dwarf Galaxy Formation by Cosmic Reionization
Observations of the highest redshift quasars suggest that hydrogen in the inter-galactic medium was reionized at a redshift prior to z=6. Following reionization, fluctuations in the distribution of galaxies contributed to a scatter in the ionizing background, and hence in the ionization fraction of cosmic hydrogen on scales of tens of Mpc, as observed along the lines of sight to the earliest known quasars. Theoretical simulations predict that the formation of dwarf galaxies should have been suppressed after cosmic hydrogen was reionized, leading to a drop in the cosmic star formation rate. In this talk I present evidence for this suppression. I will show that the post-reionization galaxies which produced most of the ionizing radiation at a redshift z~5.5, must have had a mass in excess of ~10^10 solar masses or else the aforementioned scatter would have been smaller than observed. This limiting mass is two orders of magnitude larger than the galaxy mass that is thought to have dominated the reionization of cosmic hydrogen.
July 25 @ 11:30
Raffaella Morganti (ASTRON)
Title: Gas accretion and outflows in early-type and radio galaxies
I will present recent results on the study of neutral hydrogen around early-type and radio galaxies. We have used the large-scale (tens of kpc) HI emission - in combination with information on the stellar population and ionised gas of the host galaxy - to find clues on the origin and evolution of these objects. On the nuclear (kpc) scale, fast (~1000km/s) outflows of neutral gas (from 21-cm HI absorption) have been observed and studied in strong radio sources. The outflows likely originate from the interactions between radio jets and the gaseous medium and have mass outflow rates comparable to starburst-driven superwinds. The impact on the evolution of the host galaxies will be discussed.
July 20 @ 11:30
Michael Brown (Princeton)
Title: The Assembly of Red Galaxies
We trace the assembly history of red galaxies since z=1, by measuring their evolving space density with the B-band luminosity function. Our sample of 41333 red galaxies, selected from 7 square degrees of optical and Spitzer IR imaging of Bootes, is an order of magnitude larger than comparable samples in the literature. The luminosity density of red galaxies increases by only 55 percent from z=0 to z=1. If red galaxy old stellar populations have faded by 1.2 B-band magnitudes since z=1, the stellar mass contained within the ensemble of red galaxies has roughly doubled over the past 7 Gyr. In contrast, the evolution of the most luminous red galaxies differs only slightly from a model with negligible z<1 star formation and no galaxy mergers. We find 85 percent of the stellar mass contained within today's 4L* red galaxies was already in place at z=0.7. Galaxy mergers can only slightly increase the stellar masses of luminous red galaxies between z=1 and the present day.
June 22 @ 11:30
Melanie Johnston-Hollitt (University of Tasmania)
Title: Multi-wavelength Analysis of the Double Relic Cluster A3376
A3376 is a rich, X-ray luminous, southern galaxy cluster located at a redshift of 0.046. There is evidence of a large number of galaxies in the region which are consistent with a Bautz-Morgan class of 1. The X-ray luminosity is substantial at Lx = 2.48 x 10^44 h^2_0 ergs s^-1 in the 0.4-2.4 keV range and the X-ray axis is also elongated along the same axis as the galaxy distribution. Most importantly A3376 has the distinction of being only the second galaxy cluster, after the famous A3667, to be observed with two diffuse radio emission regions on the cluster periphery. The properties of both the famous A3667 and A3376 are remarkably similar, both sharing an elongated X-ray morphology with diffuse radio emission, the so-called double relic sources, located symmetrically on either side. In addition, both clusters are at similar redshifts and possess similar X-ray luminosities and optical richness classes. The optical galaxy distributions are also shown to be elongated in both cases and roughly align with the distorted X-ray isophotes and the axis formed between the X-ray and radio emission regions. I will present the findings of a large multi-wavelength study on the dynamics of A3376 and use this to argue for a consistent physical evolution of "double-relic" clusters.
June 8 @ 11:30
Duncan Galloway (Melbourne)
Title: Accreting Binaries and the Neutron Star Equation of State
The properties of cold matter at super-nuclear density remains an outstanding problem for fundamental physics.X-ray observations of accreting neutron stars allow us to i) detect neutron stars spinning beyond the present maximum to constrain the equation of state, and ii) test for the presence of exotic matter via thermonuclear explosions in the accumulated material. I will describe the basic observational properties of accreting neutron stars, and give a progress report on an ongoing observational study of these objects. I will also briefly discuss the prospects for future tests for exotic states (e.g. "strange quark matter") in these objects.
June 2 @ 11:30
Giuseppe Cimo (University of Tasmania)
Title: Scintillation of Active Galactic Nuclei: microarcsecond Structures and the local Interstellar Medium
The spectral and polarimetric characteristics of the rapid scintillators are fundamental in order to describe both the innermost (sub-pc) regions of these compact objects and the interstellar medium producing the scintillation. Combining AT Compact Array observations with data from the monitoring projects at the University of Tasmania, a multifrequency analysis of the Intraday Variability phenomenon will be described. Furthermore it will be shown how Intraday Variability observations can been used as an instrument to model the interstellar medium and to evaluate physical parameters for the interstellar clouds. Finally the overall interpretation of the results and some implications concerning the physics of compact structures and the characteristics of the interstellar medium will be discussed.
June 1 @ 11:30
Shinji Horiuchi (Swinburne)
Title: Discovery of Precession Jets in BL Lac objects
The results of global VLBI observations for a little studied BL Lac object are presented. The disk-based recording and software correlator system was developed at Swinburne and applied for these experiments to obtain the first radio astronomical images. Archived VLBI data taken over 10 years for this source are also analysed in detail to study structure and evolution of this AGN. These results are in contrast to previous studies of this source which did not reveal significant jet motions from limited data sets. We interpret variations in the orientation of the major axis of the compact core as jet precession with a period of ~5.5 yr. The signature of the precession is clearly detected also in total flux density and polarization position angle measurements made with the Australia Telescope Compact Array (ATCA) over 10 years. Motivated by this discorvery and growing evidence of periodicities for some of BL Lac objects such as OJ 287 and BL Lacertae, we have begun to monitor a sample of 56 BL Lac objects with the ATCA to obtain statictics of jet precession.
May 25 @ 11:30
Jim Cohen (Jodrell Bank)
Title: The methanol multibeam project
A new 7-beam methanol multibeam receiver was successfully commissioned at Parkes in January, and has begun surveying the Milky Way for newly forming stars, that are pinpointed by strong methanol maser emission at 6.7 GHz. The Parkes survey of the Milky Way for methanol masers is two orders of magnitude faster than previous systematic surveys using 30-m class dishes. The first 26 days of observations have yielded 377 methanol sources, of which 150 are new discoveries. The methanol multibeam receiver is also being used in a fixed pointing mode to search for highly scattered pulsars. I will give an overview of the multibeam project and present preliminary results.
May 19 @ 11:30
James Murray (Swinburne)
Title: Black holes might have no hair but they certainly can hold a tune
May 8 @ 11:30
Willem van Straten (University of Texas)
Title: Applications of Matrix Template Matching
Fundamental to every pulsar timing experiment is a measurement known as the pulse time-of-arrival (TOA), the epoch at which a fiducial phase of the pulsar's periodic signal is received at the observatory. Pulse TOAs are typically measured using only the observed total intensity of the pulsed radio emission. A new matrix template matching technique is presented that exploits the additional timing information available in the polarization of the pulsar signal. For a number of millisecond pulsars, TOAs derived from polarization data are predicted to exhibit greater precision and accuracy than those derived from the total intensity alone. Furthermore, given a polarimetric observation of a well-determined pulsar, the technique can be used to calibrate the instrumental response in observations of other sources.
April 27 @ 11:30
Kristin Warnick (Astrophysikalisches Institut Potsdam)
Title: The sense of rotation of subhalos in cosmological simulations
I will present an overview of our analysis concerning the orientation of subhalos in cosmological dark matter halos. Host halos obtain their angular momentum from subhalos falling into the host at early times. The subhalos are connected to their environment, being channeled along the filaments surrounding the host. Thus the satellites are falling into the host from preferred directions, leading to the assumption that they are corotating with their host. We analysed nine high resolution cosmological simulations and found on average a small majority of 59% of the satellites corotating with their host, which is another prediction of the underlying LambdaCDM cosmology and might be verified observationally.
April 20 @ 11:30
Chris Flynn (Tuorla Observatory / Mount Stromlo)
Title: The mass to light ratio of the local Galactic disk
I describe a measurement of the mass-to-light ratio (M/L) of the local Galactic disc, made in the B, V and I bands. The mass of the nearby disc is already well understood from kinematic studies by a number of groups, including our own. What we add here is a measurement of the nearby disc's luminosity, based primarily on Hipparcos and the Catalog of Nearby Stars. Combining the results gets us to the M/L ratio for the disc, a quantity with interesting applications to dark matter studies, rotation curves and more. Along the way we also get to measure the colours of the Sun...
April 13 @ 11:30
D. J. Pisano (Naval Research Lab)
Title: Constraining the Nature and Evolution of Luminous Compact Blue Galaxies
Luminous Compact Blue Galaxies (LCBGs) are blue, high surface brightness, vigorously starbursting, approximately L* galaxies. They undergo strong evolution as they are common at z~1, where they contribute about 45% of the star formation in the Universe, while they are at least 10 times rarer today. LCBGs are a morphologically and spectroscopically diverse group of galaxies. We understand little about their physical characteristics and possible evolutionary paths. I report on a large, multi-wavelength survey of the uncommon, nearby LCBGs analogous to the common, distant LCBGs to better understand the properties of this class of galaxies. I will focus mainly on the radio observations of HI in these galaxies, but will also discuss CO and optical data and their role in deciphering the current nature and future evolution of LCBGs.
April 6 @ 11:30
Randall Wayth (University of Melbourne)
Title: The Mileura Widefield Array
The Mileura Widefield Array (MWA) is a new low frequency radio telescope to be built in Western Australia. Its primary science goal is to detect the HI power spectrum from the epoch of reionisation. In 2005, four trips were made to Mileura to deploy and test a 3-antenna prototype system. I will talk about the site, the challenges of building the prototype and the full array, and some of the interesting results obtained so far.
March 30 @ 11:30
Michael Daniel (University College, Dublin)
Title: Gamma Ray Astronomy: Science Drivers and VERITAS
The field of Very High Energy (Energy > 100GeV) gamma ray astronomy is well and truly in its renaissance period. The third generation of instruments has increased the source catalogue substantially, giving a new window on Super Nova Remnants (SNR), Pulsar Wind Nebulae (PWN), Active Galactic Nuclei (AGN), microquasars, as well as limits on both dark matter and the diffuse extra-galactic background radiation. It has even turned up a few objects as yet unidentified at other wavelengths. The developments in the field will be summarised in this talk and some of the most interesting results highlighted.
March 23 @ 11:30
Ralf-Jürgen Dettmar (Bochum)
Title: Gaseous halos of spiral galaxies
Using multi-wavelengths observations of edge-on galaxies a correlation of the properties of gaseous halos with the star formation in the underlying disk is established for late type galaxies. This can be understood in the framework of the so-called "disk-halo interaction" scenario and the results are discussed in the context of global models for the interstellar medium. In addition it will be shown how the halo population of cosmic rays observable in the radio continuum may help to better understand galactic dynamos.
March 10 @ 15:00
Matthew Colless (AAO)
Title: Reviewing the future of the AAO
The Australian Astronomy Decadal Plan envisions the Anglo-Australian Observatory evolving into the national optical/infrared observatory, supporting the AAT, Gemini and future national facilities. This evolutionary path must deal in the short term with the reduction in UK funding for the AAO over the next couple of years, and in the medium term with the UK's foreshadowed withdrawal from the AAT Agreement in 2010. DEST is therefore reviewing the AAO in order to determine the best way forward, in terms of positioning the AAO in the period running up to 2010 and establishing a new organizational model thereafter. In this talk I will discuss the background to the review, describe the AAO's own vision for what needs to be done, and solicit the opinions of the local astronomical community on these issues. For a summary of the background and issues, please read the review Issues Paper.
March 2 @ 12:00
Emma Ryan-Weber (Cambridge)
Title: Gas-rich galaxies in a gas-rich cosmic web
The location of low column density Lyman-alpha absorbers provides a map of the cosmic web between galaxies. I will talk about the connection between galaxies and the intergalactic medium, in particular the results from the cross-correlation of Lya absorbers and gas-rich galaxies at z=0. The analysis shows a real-space clustering signal stronger than that of galaxy self-clustering, which suggests that Lya absorbers are embedded in galaxy groups and large-scale filaments, particularly those that comprise gas-rich galaxies.
Feb 14 @ 15:30
Alister Graham (ANU)
Title: Elliptical galaxy structure and their supermassive black holes
The centers of giant galaxies - built through the collision and merger of lesser galaxies - appear partially depleted of stars. This is thought to be the result of the wrecking ball action of supermassive black holes - from the progenitor galaxies - as they sink to the center of the newly wed galaxy. We have developed an innovative, new method of analysis that has, in quantifying this damage, revealed that the galactic merger history of our universe may be some ten times less violent than previously claimed. These results will be presented in the context of an overview, if not overhaul, of our understanding of elliptical galaxy structure.
Feb 14 @ 11:30
Jarrod Hurley (Monash)
Title: Star Clusters: From the Cradle to the Grave, and Beyond
Feb 13 @ 16:00
David Blair (UWA)
Title: Phonons, Photons and Gravitons: Challenges at the Threshold of Gravitational Wave Astronomy
An Australian Consortium is participating in the LIGO project that has built two enormous gravitational wave detectors in the USA while working towards a large scale detector called AIGO at Gingin, WA. LIGO has reached its initial design goal and is the most sensitive instrument ever created. A 1.5 year detection run is underway which has only modest chance of detection, but detection will be certain when a global network is completed with improved detectors. LIGO in collaboration with ACIGA and the European GEO project is working towards an advanced detector which will increase the probed volume of the universe 1000-fold. At Gingin the consortium is developing high optical power techniques in an 80m interferometer which will be used in the future Advanced LIGO and AIGO. This talk will present the current status of gravitational wave detection and will cover some of the fascinating physics associated with very high power interferometers.
Feb 6 @ 15:00
Andrew Hopkins (Sydney)
Title: Galaxy Evolution: Star Formation, Mass, and Morphology
Feb 6 @ 10:00
Karl Glazebrook (Johns Hopkins)
Title: Reverse engineering galaxy evolution: from hierarchical assembly to cosmic downsizing
January 19 @ 11:30
Walter Brisken (NRAO)
Title: VLBA Pulsar astrometry
January 12 @ 11:30
Dominik Argast (Swinburne)
Title: Inhomogeneous Chemical Evolution: The Good, the Bad and the Ugly
Chemical abundances in stars trace the state of the interstellar medium (ISM) at the place and time of their birth. In recent years, a wealth of very accurate stellar abundance data probing the oldest stars of our Galaxy have become available. This data suggests that the ISM was chemically inhomogeneous at the very earliest stages of Galaxy formation. Classic chemical evolution models which assume a well mixed ISM at all times are therefore incapable to explain the significant scatter in stellar abundances at very low metallicities. I will give a general introduction to inhomogeneous chemical evolution, its advantages and some of the problems that have to be solved to gain a deeper understanding of the earliest stages of Galaxy formation. Time permitting, I will also discuss the astrophysical nature of the formation site of r-process elements and give a brief glimpse on ongoing projects.
January 9 @ 11:30
(half hour)
Darren Croton (Berkeley)
Title: The many lives of AGN: from super-massive black holes to host galaxy colours and luminosities
I use a semi-analytic model of galaxy formation and the Millennium Run LCDM N-body simulation to explore the evolution of the galaxy population, including super-massive black hole growth, in a cosmological context. I focus on the effect that AGN feedback has on cooling flows in massive systems, and discuss the impact that such cooling suppression has on the final galaxy properties.
January 6 @ 11:30
Michael Murphy (Cambridge)
Title: Dust in high-z damped Luman-alpha systems
High-z damped Lyman-alpha systems (DLAs) have long been hailed as the reservoirs of neutral hydrogen out of which modern-day stars formed. However, establishing a link between the observed neutral gas and actual star-formation potential requires the observation of molecular hydrogen and/or dust in DLAs. Here I discuss the evidence for dust in the overall DLA population derived from the Sloan Digital Sky Survey QSO spectra. The main result is that the average DLA between z=2.3 and 4.5 contains very little dust. The role of DLAs in star-formation at high-z is therefore questionable. Time permitting, I will also discuss the importance of dust at lower redshifts (z=0-1).