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Colloquia Series

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

Swinburne Virtual Reality Theatre
AR Building, Room 104
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2014 Colloquia

Thursday Dec 18, 10:30
Alan Duffy (Swinburne)
Colloquium: First Galaxies and DRAGONS
One of the most important questions in astronomy today is the source of the ionising photons that caused a predominantly
neutral Early Universe to evolve into the ionised one we see today. I have investigated this Epoch of Reionisation with a
a new suite of high resolution hydrodynamical simulations, created within the DRAGONS group. These simulations show
that the galaxies observed at early times represent merely the tip of an iceberg; with a hidden population of faint galaxies
that can Reionise the Universe with ease. Although the global star formation history of the early universe is strongly
constrained by current observations, we actually know little about the nature of star formation at this time (as given by the
specific star formation rate). I will demonstrate that we can understand these objects but need to push our observations deeper,
a goal that will likely have to await the James Webb Space Telescope.
Tuesday Dec 16, 11:30
Dany Vohl ()
Student Review: Dany V - 6 month review
6 month review talk
Thursday Dec 11, 11:30
Paolo Serra ()
Colloquium: Neutral hydrogen gas in early-type galaxies: results from the Atlas3D survey - Paolo Serra
We often describe galaxies at z=0 as a bimodal population. On one side we have gas-rich, star-forming spirals; on the other, passively-evolving, gas-poor, early-types. The former, with their star formation activity and complex hydrodynamics, sound like much more fun than the latter -- but is this really the case? In this talk I will present results from a large survey of neutral hydrogen gas (HI) in early-type galaxies carried out as part of the Atlas3D project. I will show that early-type galaxies form a surprisingly heterogeneous family when it comes down to HI, covering four orders of magnitude in M(HI)/M(star) and a wide range of gas morphologies. I will discuss the role of environment in shaping these properties and present results on the misalignment between the angular momenta of stars and HI in these objects. Future HI surveys will allow us to greatly expand this line of investigation and I will discuss this by giving a brief update on ASKAP commissioning.
Tuesday Dec 9, 11:30
George Bekiaris ()
Student Review: George B - 18 month review
18 month review talk
Thursday Dec 4, 11:30
Aaron Robotham (UWA/ICRAR)
Colloquium: Building galaxies: the interplay between star-formation and mergers in GAMA - Aaron Robotham
The GAMA survey has recently collected the last of its redshifts after 7 years operating on the AAT. The completeness and fidelity of this data has allowed us to construct a full picture of mass growth through in-situ star-formation and mergers between 10^8 and 10^12 Msol. Most significantly, GAMA is able to probe merger ratios down to 1:300 with robust statistics. In this colloquium I will present my recent work on the analytic form of the merger rate for all merger ratios, and how this directly drives the current evolution of the galaxy stellar mass function.
Tuesday Dec 2, 11:30
Scott Croom (USydney)
Colloquium: The SAMI Galaxy Survey
Galaxies are intrinsically complex systems, with multiple components
(disk, bulge, halo, black hole, gas, dust, stars etc) which interact
with each other in non-trivial ways. Major steps forward in physical
understanding have been possible using massive galaxy surveys, such
as 2dFGS and SDSS, but these are fundamentally limited by their having
only a single aperture per object. I will describe the Sydney-AAO Multi-object
Integral field spectrograph (SAMI), a multi-object IFU system developed jointly
by the University of Sydney and the Australian Astronomical Observatory (AAO).
Building on previous work with monolithic IFUs, SAMI is being used by an
Australian led international team to carry out a survey of over 3000 galaxies,
between 2013 and 2016. We currently have data for over 1000 galaxies in
hand. I will discuss the survey design, and science rationale, as well a range
of early science from the project.
Thursday Nov 27, 11:30
Alex Codoreanu ()
Student Review: Alex Codoreanu 6 month review
Wednesday Nov 26, 15:30
Emma Ryan-Weber (CAS)
Colloquium: Dept. of Physics & Astronomy colloquium
Tuesday Nov 25, 11:30
Student Review: 18 Month Review - Antonio Bibiano
Thursday Nov 20, 11:30
Jillian Bellovary (Vanderbilt)
Colloquium: Scrutinizing the Relationship Between Galaxies and Supermassive Black Holes
Abstract: Supermassive black holes (SMBHs) have a ubiquitous presence in massive galaxies, but their formation and evolutionary history remain mysteries. One of the strongest observed trends between SMBHs and their host galaxies is the tight relation between black hole mass and the velocity dispersion of the stellar spheroid (aka the M-Sigma relation). While this relation hints at a fundamental link between galaxy and SMBH growth, there are also some challenges regarding scatter and outliers. I will present evidence that the M-Sigma relation is not the clear-cut trend it seems to be; for example, the orientation of galaxies on the sky affects the value of velocity dispersion by up to 30%. Additionally, the existence of SMBHs in dwarf galaxies and galaxies without spheroids challenges the standard paradigm of SMBH-galaxy coevolution. I will offer some alternative methods of forming and growing SMBHs which can provide explanations for these puzzling outliers.
Tuesday Nov 18, 11:30
Themiya Nanayakkara (Swinburne)
Student Review: 18 month PhD review for Themiya Nanayakkara
18 Month PhD review
Thursday Nov 13, 11:30
Shuvo ()
Student Review: Shuvo 30 Month review
Wednesday Nov 12, 15:00
Kate Rubin (Harvard/CfA)
Colloquium: The Circumgalactic Medium in 2D: from Lineland to Flatland - Kate Rubin
Abstract: The environments extending several hundred kiloparsecs from galaxies contain the fuel that feeds galactic star formation, and act as the reservoir into which ejecta from stellar and AGN feedback are driven. Observations of the cool hydrogen and metal content, kinematics, and morphology in these regions (i.e., the circumgalactic medium, or CGM) can therefore provide incisive tests of our understanding of these processes. Focusing at z~2, I will briefly discuss current constraints on the content of the CGM around massive, >L* galaxies. I will then describe a new technique that pinpoints much fainter, sub-luminous systems at z~2, allowing us to probe the gas in their surroundings in absorption toward background QSOs. This technique has the added benefit of tracing the kinematic coherence of this material over >100 kpc scales. I will also discuss prospects for new constraints on the small-scale structure of both CGM absorption and cool material entrained in galactic winds. Such measurements represent important steps toward a complete, detailed empirical picture of the CGM.
Thursday Nov 6, 11:30
Dougal Mackey (ANU)
Colloquium: The outer halo and globular cluster system of Andromeda - Dougal Mackey
Abstract: Large galaxies are believed to form hierarchically via the merger and accretion of smaller systems over cosmological time. A galaxy's stellar halo, although constituting only a small fraction of the overall mass of the system, holds an important record of these events due to the long dynamical times far from the centre of the potential well. In this talk I will present recent results from the Pan-Andromeda Archaeological Survey (PAndAS) which has acquired deep wide-field imaging spanning almost the entire halo of M31, our nearest large neighbour. Discoveries include a plethora of halo substructures and tidal streams, the presence of an apparently smooth halo component, and an unexpectedly rich and varied population of remote globular clusters. These latter objects are proving particularly useful probes of the structure and kinematics of the M31 halo.
Thursday Oct 30, 11:30
Mark Durre ()
Student Review: Mark Durre Review
Wednesday Oct 29, 15:30
Xia-ji Liu (CQOS)
Colloquium: Dept. of Physics & Astronomy colloquium
Strongly Correlated Ultracold Fermions

Outer space may be cool, but not cool enough for physicists who have chilled a cloud of neutral atoms to one millionth degree above absolute zero temperature - the coldest temperature ever recorded. Creating a very cold atomic cloud is not just a cool achievement, it also helps physicists better understand a new form of quantum matter and enable technological innovations with huge impact in our society.

This new type of matter is a condensate of strongly correlated fermionic pairs that shows novel superfluidity in cold-atom laboratories. Its observation will help solving lingering questions such as high-temperature superconductivity, which has widespread applications for magnets, sensors and energy-efficient transport of electricity. In quantitatively understanding new experimental results, quantum many-body theory is now facing severe challenges.

In this talk, I will provide an introduction to the field of ultracold atomic physics, focusing on some recently developed theoretical techniques that are providing successful predictions in our group
Tuesday Oct 28, 11:30
Mark Hutchison ()
Student Review: Mark Hutchison's 18 month review
Thursday Oct 23, 11:30
Jean-Pierre Macquart (Curtin)
Colloquium: Whence the FRBs? - Jean-Pierre Macquart
The detection of millisecond-duration Fast Radio Bursts (FRBs) at
apparently cosmological distances has opened up new possibilities of
probing the Intergalactic Medium. The dispersion measures of FRBs
will enable us to detect the "missing" baryons in the low-redshift
Universe that constitute >50% of the baryonic mass at z~0. Several
FRBs exhibit evidence of temporal smearing by turbulence that must
reside at cosmological distances. I will discuss the likely ambient
properties of the plasma, the location of this turbulence, and
present several arguments why the bulk of the dispersion measure does
not emanate from regions near the bursts themselves. In addition, I
will investigate the suggestion that the dependence on the FRB
detection rate on Galactic latitude is due to interstellar
Wednesday Oct 22, 09:30
Rob Bassett ()
Student Review: 30-month Review - Rob Bassett
Tuesday Oct 21, 11:30
Shivani Bhandari (Swinburne University)
Student Review: Shivani Bhandari 6-month Review
Tuesday Oct 14, 15:00
Tim Bedding (Sydney)
Colloquium: A Golden Age of Asteroseismology with Kepler
Abstract: Stellar astrophysics has entered a new golden age, thanks to wonderfully precise measurements being returned by NASA's Kepler mission. Kepler is a 0.9-metre space telescope that has been monitoring the brightness of more than 100,000 stars with extraordinary accuracy for more than four years. Its main goal is to discover extra-solar planets by detecting the small dips in light as they transit their parent stars. The mission has been spectacularly successful, with thousands of candidates reported. Meanwhile, Kepler's observations of oscillations in thousands of stars have led to a revolution in asteroseismology. Key results include detecting gravity modes in red giant stars and characterizing stars found to host exoplanets.
Tuesday Oct 14, 11:30
Elodie Thilliez ()
Student Review: Elodie Thilliez's 18 month review
Friday Oct 10, 08:45
Gonzalo Diaz (Swinburne)
Colloquium: Viva Talk: Gonzalo Diaz
Open presentation on "Galaxies and the Intergalactic Medium at redshift 5.7: The Environment of Metal Absorption Systems"
Thursday Oct 9, 11:30
Paola Oliva ()
Student Review: Paola Oliva's 30-month review
Thursday Oct 2, 11:30
Tyler Bourke (Manchester / SKA)
Colloquium: The Square Kilometre Array: Science Drivers and Status Update
Abstract: The Square Kilometre Array (SKA) will be the world’s largest radio telescope when completed in the next decade. The past few years have seen great progress toward this goal, with the establishment of a project office in 2011, site selection in 2012, and detailed design work beginning in 2013. Construction will begin in 2017 with early science anticipated for 2020. In this presentation I will provide a status update on SKA activities, with a focus on the science it will enable and the avenues available for community involvement.
Wednesday Oct 1, 11:30
Manoj Kaplinghat ( (UC Irvine))
Colloquium: Special lunch talk -
"I will discuss the cusp-core problem and other unsolved problems in galaxy formation on small scales and introduce self-interacting dark matter as a compelling solution."
Thursday Sep 25, 11:30
Emily Wisnioski (MPE)
Colloquium: The KMOS^3D Survey: design, first results, and the evolution of galaxy kinematics
Abstract: I will discuss the KMOS^3D survey, a new integral field survey of over 600 galaxies at z=0.7-2.7 using KMOS at the VLT. The KMOS^3D survey utilises synergies with multi-wavelength ground and space-based surveys to trace the evolution of spatially-resolved kinematics and star formation from a homogeneous sample over 5 Gyrs of cosmic history. In the first year of data we detect Halpha emission in ~200 galaxies at z~1 and z~2 In the current sample most of the resolved galaxies are rotation-dominated implying that the star-forming ‘main sequence’ (MS) is primarily composed of rotating galaxies at both redshift regimes. The first year data and results from our KMOS^3D survey opens up new avenues in investigating the early evolution of galaxies and their kinematics.
Wednesday Sep 24, 15:30
Prof Sarah Russell (CMP)
Colloquium: Dept. of Physics & Astronomy colloquium
Title: Using physics to study immunology and cancer.

Abstract: My group's research is spread over two laboratories, located at Swinburne's Centre for Micro-Photonics and the Peter MacCallum Cancer Centre. The purpose of the Swinburne lab is to provide tools with which to conduct our research into immune cell development and function, and the origins of leukemia. I will discuss how microfabrication, computational biology and advances in microscopy are directly applied to our biological research.
Thursday Sep 18, 11:30
Neil Crighton (Swinburne)
Colloquium: The metallicity and small-scale structure of the z~2.5 circumgalactic medium
Abstract: Observations of the gaseous halos of galaxies (the circumgalactic medium) are able to constrain important but poorly-understood mechanisms that govern galaxy formation, such as supernovae-driven outflows and gas inflowing along cold-mode accretion streams. I will describe our group's observations of the gaseous halos of galaxies at redshift 2.5, near the peak of the cosmic star formation rate. We use a sample of quasar-galaxy pairs, such that a background quasar sightline passes through the halo of the foreground galaxy, to detect the foreground galaxies' halo in absorption. By comparing this absorption to photo-ionisation models, we make robust measurements of the gas metallicity and absorbing cloud size. We find one very low metallicity absorber which is consistent with theoretical predictions for cold-mode accretion. We also find metal-enriched clouds with very small (sub-kiloparsec) sizes. I will discuss how these small sizes pose a challenge for numerical simulations of galaxy formation.
Thursday Sep 11, 11:30
Caroline Straatman (University of Leiden)
Colloquium: High redshift galaxies and early retirement
Abstract: Massive quiescent galaxies, with little or no star formation, have been found in numerous quantities out to redshift z=3, when the universe was only (roughly) 2 Gyrs old. These high redshift quiescent galaxies are not entirely similar to their low redshift elliptical counterparts, as their average size is a factor of 3-4 smaller. While having low star-formation rates, they are believed to still grow in size by a number of merging events with smaller galaxies. The debate on how they assembled their mass and what causes the subsequent shutting down of star formation is still ongoing, even as observational teams are looking for more distant examples of quiescent galaxies.
Using products from the FourStar Galaxy Evolution Survey (ZFOURGE), I will show that quiescent galaxies exist even at redshift z=4. The survey uniquely combines deep imaging (Ks~25 AB mag) and a set of near-IR medium-bandwidth filters, which straddle the Balmer/4000A break up to redshift z=4.2 and enable the derivation of very accurate photometric redshifts. The newly discovered galaxies have high stellar masses (M~10^11 solar mass) and small sizes (R~0.7 kpc) and no evidence for dust-obscured star formation from ultra-deep Herschel/Pacs 100 and 160 micron data. At z=4 the universe is only 1.6 Gyr old, suggesting extremely rapid formation at early times (z>4). Comparing with the number of observed high redshift very bright Lyman Break and sub-mm galaxies, I will discuss possible progenitors for the z=4 quiescent galaxies.
Thursday Sep 4, 11:30
Duncan Forbes (Swinburne)
Colloquium: The Scaling Relations of Small Stellar Systems: Across the Star Cluster-Galaxy Divide
Abstract: Using new data from the Keck telescope I report on the scaling relations of small stellar systems, ie globular clusters, ultra compact dwarfs, dwarf and compact ellipticals. The elevated mass-to-light ratios seen in some of these systems may indicate either the presence of dark matter, central black holes or a bottom-heavy IMF. Various scaling relations are investigated to
shed light on which these interpretations is most likely. The origin of cEs and UCDs is also discussed.
Wednesday Sep 3, 11:30
Angela Garcia ()
Student Review: Angela Garcia 6 month review
Wednesday Sep 3, 15:30
Sarah Maddison (CAS )
Colloquium: Dept. of Physics & Astronomy colloquium
Title: Using observations and simulations of circumstellar disks to understand planet formation

Abstract: Planets form in the dusty disks that surround young stars, but exactly how tiny grains grow into planetary bodies is not well understood. By studying the evolution of circumstellar disks we gain valuable insights into the planet formation process. In this talk, I will discuss some of the current theories of protoplanetary disk evolution and work being done to advance our understanding of planet formation. I will highlight both observational and numerical techniques being used to study different phases of disk evolution, focusing on planet-disk interactions, what we are learning about both the gas-rich protoplanetary phase and dust-rich debris disk phase, and future directions in this field.
Tuesday Sep 2, 11:30
Luis Torres ()
Student Review: Luis Torres 18-month review
Thursday Aug 28, 11:30
Brad Tucker (MSO)
Colloquium: Results from ESSENCE and the Kepler Extra-Galactic Survey (KEGS)
Abstract: The Equation of State: SupErNovae trace Cosmic Expansion'
(ESSENCE) survey was a 6-year NOAO program which discovered 228 Type Ia
Supernovae (SN Ia) in the redshift range 0.2 < z < 0.8, to characterize the dark energy equation-of-state, w. However, due to limitations in both the knowledge of the SN Ia progenitor system and systematic errors related to influences of the host galaxies on SN Ia distances and the photometric calibrations of the survey, the measurements are only accurate to ~10%. To solve some of these issues, we developed a new method for determining the spectral energy distribution and rest-frame magnitudes of the host galaxies from the ultraviolet (UV) to the infrared and use empirical relations to derive stellar mass and star-formation rate (SFR) measurements of the host galaxies. We find a substantial amount of UV emission in our passive galaxies, suggesting star formation in these galaxies and a link between UV excess and SN Ia progenitors. Additionally, we find a 4 sigma correlation of the rest-frame far-UV minus V (FUV-V) host-galaxy color and distance residuals from the best-fitting cosmology (Hubble residual), when the sample is divided by host-galaxy type. Lastly, we find that SN Ia at > 3 effective radius of the host galaxy occur in low-extinction environments, subsequently producing a uniform sample of SN Ia which can be used to measure cosmological parameters with lower systematic errors. SN Ia at these distances have noticeable offsets in SN color and Hubble residual from the entire sample, suggesting an improper treatment of SN Ia color and dust, both of which have the potential to bias SN Ia distance measurements.

Kepler's unique technical capabilities are not only well suited for finding and studying exo-planets, but also supernovae. I will give an overview of the Kepler Extra-Galactic survey - a program using Kepler to search for supernovae, active galactic nuclei, and other transients in galaxies. To date we have found two type Ia supernovae and two core-collapse supernovae. The 30-minute cadence of Kepler has revealed subtle features in the light-curves of these supernova not detectable with any other survey. With a high-cadence, high precision survey, shock break-out in a large number of SN can be found, improving our understanding of supernova progenitors. We can also search in nearby galaxies for very fast and faint transients, filling in a previously unaccessible parameter space. Lastly, the precision data of any discovered type Ia supernova combined with ground based data can dramatically improve our use of type Ia for determining distances and measuring the properties of dark energy.

Whether you like stars, galaxies, or the Universe, this talk has something for you!
Tuesday Aug 26, 10:30
Katharina Lutz ()
Student Review: Katharina Lutz 6 month review
Thursday Aug 21, 11:30
Christian Reichardt (Melbourne)
Colloquium: Gravity waves, Neutrinos, and the oldest light in the Universe
Abstract: The cosmic microwave background (CMB) radiation is the oldest light we can see. Since it bears the imprint of the universe just after the Big Bang (at a mere 0.003% of the universe’s age today), it is a crucial tool in our quest to understand how the Universe began and what its future holds. Polarization patterns in the CMB are of particular interest for studying the neutrino masses (via gravitational lensing) and inflation (via gravity waves). Remarkably, in just the last year, the lensing and gravity wave polarization signals were detected for the first time. I will discuss these detections and future prospects for CMB polarization.
Tuesday Aug 19, 16:00
Student Review: Adam Stevens 18 month review (remote)
Thursday Aug 14, 11:30
Meredith MacGregor (Harvard CfA)
Colloquium: Deciphering Debris Disk Structure
Abstract: Nearly a hundred dusty debris disks have been spatially resolved at one or more wavelengths around nearby stars. Many of these systems bear striking resemblance to the archetype debris disk surrounding β Pic, exhibiting mid-plane optical surface brightness profiles that steepen in the outer regions of the disk. These similarities have led to the development of a uniform framework for debris disks that evokes a localized belt of planetesimals, or “birth ring,” where smaller dust grains are produced through a collisional cascade. Millimeter observations are crucial to confirming the presence of such a “birth ring” in resolved disks, since these longer wavelengths trace the thermal emission from the largest grains with dynamics similar to the parent colliding bodies. We have used the SMA and ALMA to make 1.3 millimeter observations of the debris disk surrounding the nearby (9.9 pc), ~10 Myr-old, M-type flare star AU Microscopii. These millimeter observations reveal a belt of dust emission that peaks at a radius of 40 AU, in close agreement with the outer edge of the hypothesized “birth ring.” The ALMA observations also reveal a previously unknown central emission peak, ~6 times brighter than the stellar photosphere at these wavelengths. This central component remains unresolved and could be explained by stellar activity or an inner planetesimal belt located <3 AU from the star. Future observations with higher angular resolution will be able to distinguish between these possibilities.

Despite this characteristic radial architecture, many debris disks exhibit additional substructure such as brightness asymmetries, offsets, warps, and clumps that cannot be explained by the steady-state collisional models assumed in the “birth ring” framework. We have recently used the SMA to make 1.3 millimeter observations of the debris disk surrounding HD 15115, an F-type star also located in the β Pictoris moving group. This nearly edge-on debris disk (the “Blue Needle”) has been previously well-resolved in optical scattered light and displays an extreme asymmetry. In addition to a circumstellar belt of thermal dust emission, these new millimeter observations show a tentative ∼ 3σ feature coincident with the asymmetry previously seen in scattered light observations.

Thursday Aug 7, 11:30
Nicola Pastorello ()
Student Review: Nicola Pastorello 30-month review
Wednesday Jul 30, 15:30
James Chon (CMP)
Colloquium: Dept. of Physics & Astronomy colloquium
Gold nanoparticle spectroscopy for nano- bio- photonic applications
Wednesday Jun 25, 15:30
Chris Blake ((CAS))
Colloquium: Dept. of Physics & Astronomy colloquium
Title: Testing gravitational physics with cosmological observations

Abstract: The apparent existence of "dark energy" points to a failure in our physical understanding of the universe. Large surveys of galaxies can help address this mystery by mapping out both cosmic distances and gravitational physics in a variety of ways. In this talk I will present two new measurements of gravitational effects based on large galaxy samples -- firstly the (relativistic) gravitational lensing of light around foreground galaxies, detected in the distortions in the shapes of background galaxies, and secondly in the (non-relativistic) radial velocities of the same foreground galaxies relative to their nearby clusters and voids. By combining these measurements we obtain a new test of standard cosmology.
Thursday Jun 12, 11:30
Fulvio Melia (University of Arizona)
Colloquium: The Zero Active Mass Condition in FRW Cosmologies
The standard model of cosmology is based on the Friedmann-Robertson-Walker
(FRW) metric. Often written in terms of co-moving coordinates, this elegant and
highly practical solution to Einstein's equations is based on the Cosmological
principal and Weyl's postulate. But not all of the physics behind such symmetries has yet been recognized. We invoke the fact that the co-moving frame also happens to be in free fall to demonstrate that the FRW metric is valid only for a medium with zero active mass. In other words, the application of FRW appears to require an equation-of-state rho+3p = 0, in terms of the total energy density rho and total pressure p. Though the standard model is not framed in these terms, the optimization of its parameters brings it ever closer to this constraint as the precision of the observations continues to improve.

Thursday Jun 5, 14:30
Joss Bland-Hawthorn (University of Sydney)
Colloquium: The Gaia satellite: a billion stars in motion
In December 2013, the remarkable Gaia project became a reality with the successful launch of the ESA satellite. This will lead to astonishing new insights on the nature of the Galaxy and the Local Group. In just a few years, more than a billion stars will have 6D phase space information. Australia is already heavily invested in huge stellar surveys like RAVE, GALAH and FunnelWeb, but these will benefit enormously from the impending data deluge from Gaia. I will show that Australia is well positioned to capitalise on this open-access ESA mission.
Thursday May 29, 11:30
Damien Hicks (Swinburne)
Colloquium: Nuclear fusion and the control of extreme states of matter
Abstract: Laser-driven nuclear fusion involves compressing and heating hydrogen isotopes to billions of atmospheres and millions of degrees. Net energy gain results when these conditions are held stable for tens of picoseconds - enough time to ignite a thermonuclear burn wave. This talk is an overview of a major international effort to achieve ignition at Lawrence Livermore National Laboratory and the difficulties encountered in creating and controlling such extreme states of matter.
Wednesday May 28, 15:30
TBD ()
Colloquium: Dept. of Physics & Astronomy colloquium
Tuesday May 27, 10:30
Student Review: Genevieve Shattow's 30 month review
Thursday May 22, 11:30
Paul Butler (Carnegie Observatories)
Colloquium: Exoplanets searches with PFS and APF
Abstract: Abstract: Modern science began with Copernicus speculating that the Earth is a planet and that all the planets orbit the Sun. Bruno followed up by speculating that the Sun is a star, that other stars have planets, and other planets are inhabited by life. For this and other heresies, Bruno was burned at the stake in a public square in Rome in 1600. Astronomy and extrasolar planets were a really hot field at the time.

Over the past 20 years more than a thousand extrasolar planets have been found, first from ground-based precision Doppler and photometric transit surveys, and more recently by the Kepler space mission. We have concentrated on building precise Doppler systems to survey the nearest stars. Our systems at Lick, Keck, AAT, and Magellan have found hundreds of planets, including 5 of the first six planets, the first saturn-mass planet, the first neptune-mass planet, the first terrestrial mass planet, and the first multiple planet system.

We are currently focusing our attention on new custom built "R4" echelle spectrometers designed for Iodine cells, which are yielding 1 m/s precision. These spectrometers have a footprint about the size of a ping pong table, allowing for temperature stabilization, yet deliver higher resolution and dispersion than the much larger classic echelle spectometers, such as the Lick Hamilton, the AAT UCLES, and the Keck HIRES. The two working examples, PFS on the 6.5-m Magellan, and the Levy spectrometer on the 2.4-m APF, cost about US$2M each. They do not use fibers or scrambling, and have throughput of 20 to 30%, a factor of 2 to 4 better than classic echelles. These spectrometer will lead to the discovery of many terrestrial mass and potentially habitable planets over the next decade.
Tuesday May 20, 15:00
Luca Rossi (Swinburne)
Student Review: Luca Rossi 6-month Review
6 month review
Thursday May 15, 11:30
Srdan Kotus ()
Student Review: Srdan Kotus 6-month review
Tuesday May 13, 11:30
Giulia Savorgnan ()
Student Review: Giulia Savorgnan's 18-month review
Thursday May 8, 11:30
Marc Rafelski (Caltech/IPAC)
Colloquium: Metallicity Evolution and Star Formation Properties of Damped Ly-alpha Systems
Abstract: Damped Ly-alpha systems (DLAs) trace most of the neutral atomic-dominated hydrogen (HI) gas at high redshift, are thought to be progenitors of modern day galaxies, and therefore provide an important observational constraint on the formation and evolution of galaxies. While we have extensively measured the star formation from star-forming regions of high redshift galaxies, we know relatively little about the star formation in HI rich regions. I will show that the star formation rate efficiency of HI gas at z~3 is more than a factor of 10 lower than predicted by the local Kennicutt-Schmidt relation. There are multiple possible causes of the reduced SFR efficiency, and the low dust content and metallicity of DLAs likely contributes. I will present chemical abundance measurements of DLAs out to z~5, which we use to determine the evolution of the cosmic metallicity of neutral gas. We find a statistically significant linear decrease in the cosmic metallicity with increasing redshift. There is also evidence for a sudden rapid decrease in the chemical abundances at z>4.7, which may represent a transition in the nature of DLAs above z~4.7. I will also show that the metallicity distribution and the alpha/Fe ratios of z>2 DLAs are consistent with those of halo stars, making it possible that the halo stars in the Milky Way formed out of DLA gas. I will demonstrate that while DLAs contribute only a small fraction of the total metal budget of the universe at z~2, their contribution significantly increases by z~4.
Wednesday May 7, 11:00
Adam Stevens (CAS) & Iurii Mordovin (CQOS) ()
Colloquium: Physics Graduate student seminar
Adam Stevens (CAS): Where do galaxies end?
Cosmological hydrodynamic simulations provide a natural theoretical counterpart to observational surveys which aim to measure the integrated properties of galaxies. The main advantage of simulations is knowing where everything is and how much of it there is, allowing “direct” calculations of the properties of simulated galaxies. Although we might like to think of galaxies as individual objects, they’re ultimately part of larger cosmic structure; the baryonic content they’re composed of extends to arbitrarily large radii. To have any concept of integrated properties, we need to define a surface where only everything within it comprises a galaxy. Many techniques have been used in the literature for defining this surface for simulated galaxies. After outlining some basics of hydrodynamic simulations, I will show the differences in measured properties those definitions can give and motivate a new technique of my own that can be applied to a simulated galaxy of any size or type.

Iurii Mordovin (CQOS): CRF Induced Association of Ultracold Molecules in Rb
Recently two theoretical papers proposed radiofrequency-induced coupling of atomic scattering states with a bound molecular state to induce Feshbach resonances at arbitrary magnetic fields. We report the first observation of predicted resonances for a mixture of two states |1, -1> and |2, +1> in 87Rb. Sudden increase of atom losses in narrow ranges of rf-frequencies clearly indicates the molecule association. We successfully created diatomic molecules in five different bound states and mapped their energies in the magnetic field range from 0.15 to 3.3 Gauss. From the interpolated data we determine zero-magnetic field energies of molecules with high precision (uncertainty is better than 0.1%). We also worked out a simple theory on the molecule formation rate and developed an explanation for observed asymmetries of observed resonant curves. New method of molecule association can be employed with any other mixtures of atoms and used for creation and studying new molecules.

Tuesday May 6, 11:30
Busola Alabi ()
Student Review: Busola Alabi's 6-month review
Thursday May 1, 11:30
Christopher Usher (Swinburne)
Colloquium: The Stellar Populations of Extragalactic Globular Clusters
Abstract: Observable at much greater distances than resolved stars, globular clusters provide important clues to galaxy evolution. It has been known for two decades that the colour distributions of globular clusters in almost all galaxies are bimodal. This colour bimodality has been traditionally interpreted as metallicity bimodality which would imply each galaxy experienced two phases of globular cluster formation. However, it has been suggested that the colour bimodal is an artefact of a strongly non-linear colour-metallicity relation and that the true globular cluster metallicity distributions are single peaked. Using metallicities derived from spectra from the SLUGGS survey for over 1000 GCs in 13 galaxies, I have shown that colour does trace metallicity and that most galaxies have bimodal globular cluster metallicity distributions. Additionally, using this dataset I have found evidence that the globular cluster colour-metallicity relation varies from galaxy to galaxy, contrary to the common assumption that this relation is the same for all galaxies.
Wednesday Apr 30, 15:30
Baohua Jia from CMP ()
Colloquium: Dept. of Physics & Astronomy Colloquium
We're delighted to announced the third Department of Physics & Astronomy colloquium, to be held on Wednesday 30th April at 3.30pm in EN102. This month's speaker is Associate Professor Baohua Jia from CMP, whose talk is entitled "Advanced light management in solar cells with nanostructures". Wine & cheese will be served after the colloquium in the staff room in EN612.
Wednesday Apr 30, 11:30
Rebecca Allen (Swinburne)
Student Review: Rebecca Allen's 18-month review
Thursday Apr 24, 11:30
Terrence Tricco (Monash)
Colloquium: Magnetic Fields in Star Formation
Abstract: Magnetic fields are ubiquitous throughout the Universe, and are the cause of and solution to many problems in theoretical astrophysics. I have studied the importance of magnetic fields on star formation using numerical methods I have developed for Smoothed Particle Magnetohydrodynamics. In particular, these developments have resolved issues related to upholding the divergence-free constraint on the magnetic field and with capturing shocks in weak magnetic fields. I have used these methods to study a range of astrophysical phenomena, such as jets from forming stars, magnetised turbulence in molecular clouds, and magnetic instabilities in accretion discs. In this talk, I will discuss the numerical advancements I have developed and the results obtained on problems in star formation.
Wednesday Apr 23, 15:00
Bruno Leibundgut (ESO Office for Science)
Colloquium: Supernova 1987A - spectacular physics
Abstract: The explosion of SN 1987A has provided us with the opportunity to learn more about core collapse supernovae than with any other event. The evolution of this object has been followed in great detail with all available observing facilities and delivered an unprecedented record of this explosion. There are many unique observations of this object: the neutrino burst indicating the collapse to a neutron star, the early evolution giving evidence that the progenitor star was a compact blue giant star and that there must have been significant mixing of the elements within the explosion, the circumstellar ring - presumably a remnant of the stellar evolution of the progenitor star, the formation of dust in the ejecta, and the shock interaction of the supernova ejecta with its surrounding. SN 1987A is the first supernova, where we can observe the inner ejecta directly and can also follow the effects of shocks on the ring and the ejecta. I will present the history of this unique event and the latest results showing how the supernova has entered a new phase.
Thursday Apr 17, 11:30
Marc Huertas-Company (Paris, GEPI)
Colloquium: The impact of environment on the structural evolution of massive early-type galaxies
Abstract: The assembly of the most massive galaxies of the Universe is still an open issue. In particular the structural evolution of massive early-type galaxies (ETGs) has raised a lot of attention in the past years and remains an
unsolved issue. Even though it is now well accepted that some of these galaxies were more compact in the early universe, the exact mechanisms provoking the growth are still debated in the literature. I will show in my
talk how environment can be used to put additional constraints on the physical processes responsible for the size evolution of massive ETGs. I will focus on some recent observational results showing the dependence of the structural properties of ETGs on large scale environment (from clusters to field) from z~1.5 to z~0 which I will confront with the predictions of state-of-the art semi-analytical and halo occupation distribution (HOD) models. Based on that comparison, I will discuss which physical mechanisms (mergers, disk instabilities, gas dissipation...) are more relevant in driving the relation between structure and environment of massive ETGs at different redshifts.
Thursday Apr 10, 11:30
Toby Brown ()
Student Review: Toby Brown's 6-month review
Tuesday Apr 8, 11:30
Ivo Labbe (Leiden)
Colloquium: The first billion years of galaxy evolution
Abstract: Understanding when the first galaxies form and how they evolve into the population of the present day universe is one of the most exciting and challenging questions of modern astronomical research. Ultradeep imaging surveys with the Hubble Space Telescope and Spitzer Space Telescope are now revealing thousands of galaxies in the very distant universe with redshifts of 4 and greater, up to and including z~10. However, fundamental questions remain: when did the earliest galaxies form? What determines galaxy growth? What are the descendants of these earliest galaxies? I will provide an overview of recent results, focusing on galaxy properties in the first billion years, and speculate on what we might learn with next-generation facilities such as ALMA, JWST, and 20-40m class telescopes.
Thursday Apr 3, 11:30
Elisa Boera ()
Student Review: Elisa Boera's 30-month review
Tuesday Apr 1, 11:30
Andrew Johnson ()
Student Review: Andrew Johnson 18-month PhD review
Thursday Mar 27, 11:30
Fabian Jankowski ()
Student Review: Fabian Jankowski's 6-month review
Fabian Jankowski's 6-month review
Friday Mar 21, 14:30
Darren Croton ()
Colloquium: Department colloquim
How to model the Universe in N easy steps (N>>1)

Much progress has been made in recent years in our understanding of the co-evolution of galaxies and supermassive black holes, and their connection to the underlying large-scale dark matter structure. In this talk I will discuss simulation and modelling techniques that bridge theories of galaxy and black hole formation with the properties of observed galaxy populations. In addition, I will discuss a number of open questions important for extra-galactic astronomy and cosmology, and explain how future large-scale surveys and galaxy formation models may jointly address them.
Thursday Mar 20, 11:30
Ignacio Ferreras (University College, London)
Colloquium: Understanding the formation of massive galaxies through stellar populations
Abstract: Massive galaxies represent ideal laboratories to test our knowledge of
structure formation and the connection between the assembly of dark matter halos (simply driven by gravity) and the formation of galaxies (controlled by a much more complex "baryon physics"). In this talk I will present an overview of recent work focusing on the so called two-phase formation scenario through the analysis of the stellar populations in massive galaxies from low (z<0.1) to intermediate redshifts (z~1.5). The analysis of spectroscopic observations of massive galaxies over the past 9 Gyr of cosmic history reveals an intriguing decoupling between the formation of the core, in an early and efficient burst, and the outer envelope, whose formation takes place at later times. The observational findings gathered over the past few years provide very strong constraints on models of galaxy formation and evolution, from the rate of mass assembly via mergers, to the physics of star formation in extreme environments.
Thursday Mar 13, 11:30
Chris Usher (Swinburne)
Colloquium: TBA
Abstract: TBA
Wednesday Mar 12, 10:30
Genevieve Shattow ()
Colloquium: Physics Graduate student seminar
Physics Graduate student seminar : AstroTour!
Tuesday Mar 4, 10:30
Emily Petroff ()
Student Review: Emily Petroff 18-month review
Monday Mar 3, 10:00
Dr. Patrick McCarthy (Director of the GMT) (Carnegie Observatory)
Colloquium: The Giant Magellan Telescope Project
Abstract: The Giant Magellan Telescope project is an international collaboration to design, build and operate a 25m telescope for research in exoplanet science, general astrophysics and cosmology. The consortium is composed of the ANU, Astronomy Australia Limited, the Korea Astronomy and Space Science Institute and several US universities and research institutes. The GMT primary mirror is comprised of seven 8.4m diameter segments, providing both a collecting area and diffraction-limited image concentration that are an order of magnitude better than those offered by current facilities. The telescope will be located at Las Campanas Observatory in Chile and will access the same region of the sky as SkyMapper, LSST, MWA/SKA, ALMA and a number of other surveys and front-line facilities.

I will review the scientific goals of the project and the current technical status. The project has recently passed a series of rigorous design and cost reviews and is preparing to start the construction phase. The GMT will have the widest field of view of any of the proposed ELTs. Adaptive optics is integral to the telescope via a segmented adaptive secondary mirror. These attributes will position GMT to advance astrophysics on a broad front, addressing key problems in the study of potentially habitable planets, galaxy and structure formation, chemical evolution in the Milky Way, as well as cosmology and fundamental physics.
Tuesday Feb 25, 14:00
Prof. Tim de Zeeuw (Director General ESO) (ESO)
Colloquium: ESO: Present and Future
ESO is an intergovernmental organization for astronomy founded in 1962 by five countries. It currently has 14 Member States in Europe with Brazil poised to join as soon as the Accession Agreement has been ratified. Together these countries represent approximately 30 percent of the world’s astronomers. ESO operates optical/infrared observatories on La Silla and Paranal in Chile, partners in the sub-millimeter radio observatories APEX and ALMA on Chajnantor and is about to start construction of the Extremely Large Telescope on Armazones.
La Silla hosts various robotic telescopes and experiments as well as the NTT and the venerable 3.6m telescope. The former had a key role in the discovery of the accelerating expansion of the Universe and the latter hosts the ultra-stable spectrograph HARPS which is responsible for the discovery of nearly two-thirds of all confirmed exoplanets with masses below that of Neptune. On Paranal the four 8.2m units of the Very Large Telescope, the Interferometer and the survey telescopes VISTA and VST together constitute an integrated system which supports 16 powerful facility instruments, including adaptive-optics-assisted imagers and integral-field spectrographs, with half a dozen more on the way and the Extremely Large Telescope with its suite of instruments to be added to this system in about ten years time. Scientific highlights include the characterisation of the supermassive black hole in the Galactic Centre, the first image of an exoplanet, studies of gamma-ray bursts enabled by the Rapid Response Mode and milliarcsec imaging of evolved stars and active galactic nuclei. The single dish APEX antenna, equipped with spectrometers and wide-field cameras, contributes strongly to the study of high-redshift galaxies and of star- and planet-formation. Early Science results obtained with the ALMA interferometer already demonstrate its tremendous potential for observations of the cold Universe.
The talk will summarize ESO’s current program and consider perspectives for the coming decades.
Tuesday Feb 25, 11:30
Giovanni Carraro (ESO)
Colloquium: Properties and origin of the old, metal rich, star cluster, NGC 6791
Abstract: In this talk I summarize the unique properties of the old, metal rich, star cluster NGC 6791, with particular emphasis on its population of extreme blue horizontal branch stars. I then conclude providing my personal view on the origin of this fascinating star cluster.

Friday Feb 21, 11:30
Elisabete da Cunha (MPIA)
Colloquium: The cosmic evolution of molecular gas in galaxies: predictions for (sub-)millimeter line and continuum deep fields
Abstract: Modern (sub-)millimeter/radio interferometers such as ALMA, JVLA and the PdBI successor NOEMA will enable us to measure the dust and molecular gas emission from galaxies that have luminosities lower than the Milky Way, out to high redshifts and with unprecedented spatial resolution and sensitivity. This will provide new constraints on the star formation properties and gas reservoir in galaxies throughout cosmic times through dedicated deep field campaigns targeting the CO/[CII] lines and dust continuum emission in the (sub-)millimeter regime. I will present empirical predictions for such line and continuum deep fields. We base these predictions on the deepest available optical/near-infrared data on the Hubble Ultra Deep Field. Using the physically-motivated spectral energy distribution model MAGPHYS, we fit the observed optical/near-infrared emission of 13,099 galaxies with redshifts up to z=5, and obtain estimates of their stellar mass, star formation rate, dust attenuation and dust luminosity. We combine the attenuated stellar spectra with a library of infrared emission models spanning a wide range of dust temperatures to derive statistical constraints on the dust emission in the infrared and (sub-)millimeter which are consistent with the observed optical/near-infrared emission in terms of energy balance. Our method allows us to estimate, for each galaxy, the (sub-)millimeter continuum flux densities, as well as the CO and [CII] line luminosities (using empirical relations between these line luminosities and the infrared luminosity of star-forming galaxies). We use our predictions to discuss possible deep field strategies with ALMA, and compare them with a first molecular scan obtained with the PdBI. I will also briefly discuss the effect of the cosmic microwave background on high-redshift (sub-)millimeter observations.
Thursday Feb 13, 11:30
Ricardo Demarco (Universidad de Concepcion)
Colloquium: Early-type galaxy formation: understanding the role of the environment
Abstract: One of the most characteristic features of galaxy clusters is the so-called “red sequence” (RS) that early-type galaxies form in the color-magnitude space of filters chosen to straddle the rest-frame 4000 A-break feature in galaxy spectra. Since these galaxies are, in general, devoid of gas and dust, their red colors are mainly a consequence of their passive nature. The denser cluster core is dominated by these “red-and-dead” galaxies, some of them the most massive galaxies known. However, the physical mechanisms responsible for quenching their star formation, thus originating the RS, are poorly understood. Environmental effects should play a significant role in the formation of the RS by transforming the observed galaxy properties from late to early-type ones. However, the details of how this actually happens are still unclear. I will present part of the work in progress that our team at UdeC is carrying out to better understand whether nature or nurture dominates in the formation of the RS. In this respect, I will briefly present our KMOS program aimed at studying the kinematical structure of cluster galaxies at 0.8
Friday Feb 7, 15:30
Peter Drummond (CQOS (fka: CAOUS))
Colloquium: Combined physics colloquim
Peter Drummond will present the first combined physics talk, entitled "Quantum simulations of the early universe", in EN103 at 3.30pm on Friday 7 February
Wednesday Feb 5, 15:00
Marco Drewes (Munich)
Colloquium: How many new particles do we need after the Higgs?
Abstract: The discovery of the Higgs boson completes the experimental confirmation of the Standard Model of particle physics, which achieves to describe almost all phenomena observed in nature in terms of a few symmetry principles and a handful of numbers, the constants of nature. Neutrino oscillations are the only confirmed piece of evidence for physics beyond the Standard Model found in the laboratory. They can easily be explained if the neutrinos have partners with right handed chirality like all other fermions. Remarkably, right handed neutrinos can simultaneously explain two long standing puzzles from cosmology, namely Dark Matter and the baryon asymmetry of the universe. I will discuss how close the minimal extension of the Standard Model by right handed neutrinos can bring us to a complete theory of nature and which role astrophysics will play to test these ideas.