Potential PhD Topics
PhD Supervisors
(Updated 30/01/2012)
Below are listed those CAS staff who are currently looking for PhD students. Note that this does not mean they will always have specific projects listed in the next section of this page. Often it's best to talk to the supervisor first and, upon discussing your interests and skills with them, a project may emerge.
PhD Projects
(Updated 30/01/2012)
The following list outlines particular PhD projects currently on offer. Contact the staff member(s) listed for more information. Note that, due to the nature of research, this list constantly changes; potential PhD candidates are encouraged to contact the relevant staff member(s) as soon as possible. Other projects, not listed here, may be possible; contact the staff member above whom you feel is most suited to your ideas and areas of interest.
Prof. Matthew Bailes:
The High Time Resolution Universe Survey
Dr. Chris Blake:
Cosmology in a clumpy Universe: was Einstein right?
Testing the cosmological model using the topology of large-scale structure
Prof. Warrick Couch:
Major clusters mergers as drivers of galaxy transformation and evolution
A.Prof. Darren Croton:
Building Universes
Prof. Duncan Forbes:
Unveiling the dark halos of elliptical galaxies
A.Prof. Alister Graham:
Black Holes
Dr. Glenn Kacprzak:
Detecting the faint remnants of galaxy assembly
Dr. Virginia Kilborn:
Gas accretion in nearby spiral galaxies
A.Prof. Sarah Maddison:
Photoevaporation in dusty protoplanetary disks
Searching for hidden planets
Prof. Jeremy Mould:
Constraining the properties of Dark Energy with a larger sample of Type Ia Supernovae
Scaling relations for disk galaxies
The inner workings of radio active galaxies
Dr. Emma Ryan-Weber:
Clues to the evolution of Universe from intergalactic elements
Independent galaxy distances from neutral hydrogen maps
Project descriptions
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Black Holes
Supervisor: A.Prof. Alister Graham Super-massive black holes, one million to one billion times more massive than our Sun, reside at the heart of most galaxies - including our own Milky Way. Through a careful image analysis of many galaxies' structural components, using data from the Hubble Space Telescope and elsewhere, this project will determine how these enigmatic objects have coevolved with their host galaxy. A scholarship is available to work specifically with A.Prof. Alister Graham commencing in 2012. |
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Supervisors: A. Prof Darren Croton & Dr. Greg Poole
This project will involve the construction and analysis of large supercomputer simulations of dark matter and galaxies in enormous cosmological volumes. Depending on students interest, these simulations can be used to study:
The simulation resources available for this project include the Millennium Simulation and the Gigaparsec WiggleZ (GiggleZ) Simulations, a very large suite of simulations created at Swinburne, designed for studies of cosmology and galaxy formation. Interested students will also have the opportunity to participate in the next-generation simulation program currently under design for Swinburne's recent multi-million dollar supercomputer upgrade. |
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Clues to the evolution of Universe from intergalactic elements
Supervisor: Dr. Emma Ryan-Weber How did the Universe turn from a foggy gas to transparent space sprinkled with matter? The details surrounding the end of the dark ages are among the final unknowns in modern astronomy. We have yet to discover when the starlight from the first galaxies lit up the Universe, ionizing the surrounding neutral hydrogen gas. This process is known as reionization. The aim of this project is to detect elements (e.g. carbon, silicon) in the early Universe. It involves spectroscopy on the Keck telescope at optical and near-IR wavelengths. The close link between the ionizing flux from stars and the elements they produce allows us to make a measurement of the number of ionizing photons emitted in the early Universe. The second phase of the PhD will look further into the question of the ionization state of the intergalactic medium during and after reionization. Does the number density of elements in low and high ionization states change with redshift and galaxy density? |
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Supervisors: Prof. Jeremy Mould & Dr. Chris Lidman (Australian Astronomical Observatory)
More than 10 years have now past since observations of distant Type Ia supernovae showed that the expansion of the Universe is currently accelerating. Understanding what drives the acceleration is a very active area of research. Since this discovery, both the number of supernovae and the quality of the observations have increased enormously. One of the largest surveys is the Supernova Legacy Survey (SNLS), a five year survey to find hundreds of supernovae. Results from the first three years of the survey, which are based on 250 spectroscopically confirmed supernova, are now appearing in the literature. Einstein's cosmological constant, in which the dark energy equation of state is -1 and does not change with time, is consistent with all current data, but so is dynamical dark energy, in which the equation of state parameter is not -1 and changes with time.
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One of the limitations of the SNLS survey was the lack of
time to follow all supernovae spectroscopically when the
supernovae were still bright enough to observe. It is
expected that there are around 800 supernovae with good
light curves in the full 5-year dataset. Only about half of
these have a spectrum. Currently, only supernovae that have
a spectrum are used to constrain the nature of dark
energy. If one could obtain the redshifts of the supernovae
that could not be observed, then one would double the number
of supernovae from the SNLS survey that could be used to
constrain the dark energy equation of state parameter. One
way of getting these redshifts is to obtain the redshifts of
the hosts of the supernovae.
The aims of this thesis are to obtain host galaxy redshifts for all photometrically identified SNe in the 5-year SNLS survey and to combine these redshifts with the supernovae lightcurves and the properties of the host galaxy to improve the current constraints on the dark energy equation of state parameter. This work will develop techniques that will have to be used in the next generation of supernovae surveys, such as the supernova survey with the Dark Energy Camera, which will discover thousands of supernova. |
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Supervisor: A.Prof. Chris Blake
Is dark energy an illusion caused by our interpretation of observations within a clumpy, or inhomogeneous, Universe? Our standard cosmological model assumes that the Universe is homogeneous and isotropic, which forms the basis of all cosmological measurements. The effect of inhomogeneities arising from the clusters and voids which pervade the Universe has been strongly debated. Two important observational tests of these effects are (1) to measure how the expansion rate of the Universe varies from place-to-place, relative to clusters and voids, and (2) to use the density field mapped by galaxy surveys to predict the velocity field, and thereby perform a consistency check of gravitational theory. These measurements are within the grasp of new surveys with the Australian Square Kilometre Array Pathfinder (ASKAP). This project will examine these tests in detail, using initially N-body simulations, and later real ASKAP data.
A scholarship is available to work specifically with A.Prof. Chris Blake commencing in 2012.
Supervisor: Dr. Virginia Kilborn
The fraction of the available baryons in the dark matter halos around galaxies like our own Milky Way that have cooled and been transformed into stars is only around 20 percent. If we compare the star formation rates in these galaxies to the amount of atomic and molecular gas that they contain, we infer that gas should be accreting from the external environment in order maintain star formation at its observed level. There is observational evidence - such as neutral hydrogen (HI) cloud complexes, HI-rich dwarfs in the vicinity of spiral galaxies, extended and warped outer layers of HI in spiral galaxies - that nearby galaxies accrete material in the form of atomic gas. Systematic surveys of such features are still lacking, however, so their ubiquity and their link to the growth of galactic disks still remains poorly understood. The student will observe a sample of very gas-rich galaxies to determine how these galaxies accreted their gas, and how it is transported into the disk. This project is part of a larger study into the accretion of gas onto spiral galaxies.
Supervisor: Dr. Glenn Kacprzak
The hierarchical model of galaxy formation predicts that minor mergers and interactions are responsible for building and shaping all large present day galaxies. These minor mergers do not destroy the pre-existing stellar disks of these massive galaxies, however, the less massive satellite galaxies become tidally disrupted as they approach the massive hosts. During the merger process, as the satellite galaxy degrades in orbit and soon becomes cannibalized, remnant stellar tidal features are produced and create an extend stellar halo surrounding the central galaxy (As seen with the large Magellanic stream around our own galaxy!). Cosmological models have suggested significant variations in the level and the epoch of minor mergers, implying observationally detectable variations in the quantity of tidal debris within halos as a function of time. Therefore, a detailed comparison between the predicted and observed prevalence of stellar tidal debris around disk galaxies, as a function of time, would provide deep insights and constraints on galaxy formation and evolution scenarios. However, given the low surface brightness of these features, only a handful of qualitative studies have been done to date in the local Universe.
| Using clever image analysis techniques, we will study the tidal debris around disk galaxies from 10 billion years ago to the current epoch. The goal of this PhD project is to apply these newly pioneered techniques to large imaging surveys in order to study and decipher how galaxies are built as a function of time. The student will be involved in detailed data processing and analysis, providing the potential of producing several quality publications. This project has a variety of directions and can be tailored to the student interests (please feel free to ask about these project directions!). There is no doubt that the quality of the science produced here, along with the skill set developed during this project, will provide the student with the scientific footing required for a successful career in astrophysics. In addition, the candidate will also be provided with opportunities to form collaborations with colleagues overseas. |
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Independent galaxy distances from neutral hydrogen maps
Supervisor: Dr. Emma Ryan-Weber Edwin Hubble was the first to make the connection between the distance to galaxies and their recessional velocity due to the expansion of the Universe. The key to his discovery was the method to measure galaxy distances independent of their velocity. The aim of this PhD project is to develop a novel technique to measure independent galaxy distances from neutral hydrogen maps. The project will involve observations at existing telescopes such as the Australia Telescope Compact Array ( ATCA) and the findings will hold wide reaching implications for the interpretation of neutral hydrogen data from the next generation of radio telescopes (e.g. ASKAP). The second phase of the PhD will involve producing large scale cosmological flow maps of the local Universe (see Figure) based on the student's independent distance measurement technique. |
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Supervisors: Prof. Warrick Couch & Dr. Matthew Owers
The most extreme form of structure formation in the Universe occurs when two massive clusters of galaxies merge to form a single entity. This violent event vigorously rearranges the environment of the residing galaxies and simulations suggest that this process may result in an enhancement in the mechanisms which drive the transformation of spiral galaxies into elliptical galaxies. Furthermore, recent observations of merging clusters at radio wavelengths have hinted at an increase in the number of galaxies which have undergone a recent episode of intense star formation activity -- an excellent signature of a galaxy in the throes of rapid evolution. However, the increase in the population of these galaxies is not ubiquitous amongst merging clusters and the emerging hypothesis is that the details of the cluster merger are key factors in understanding the ifs, hows and whys of cluster merger induced galaxy transformation.
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This project will involve the analysis of Giant Metrewave
Radio Telescope observations of three merging clusters of
galaxies for which deep Chandra X-ray observations and
comprehensive multi-object optical spectroscopy (MOS)
exist. The Chandra and MOS data have been used to place
tight constraints on the dynamical history of the mergers
and the radio data can now be exploited to test the
relationship between the merger parameters and the radio
galaxy population in merging clusters. In combination with
the study of the optical spectral properties the galaxies in
these clusters, the radio data offers an excellent
opportunity to undertake a detailed investigation of the
effects of cluster mergers on the resident galaxies.
During the project, the candidate will acquire skills in reducing and analysing radio data -- a much desired skill given Australia's involvement in future surveys to be undertaken with the Australian Square Kilometre Array Pathfinder radio telescope. The candidate will also be provided with opportunities to form collaborations with colleagues based around Australia and overseas. |
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Supervisor: A.Prof. Sarah Maddison
Planets form in dusty disks around young stars. Observations show that most young stars (~106 yrs) are surrounded by dusty protoplanetary disks, but by about 107 yrs most disks have dissipated, which puts strong constraints on the timescales of planet formation. The fact that so few transitional disks have been detected further suggests that the disk dispersal phase must be very short, of order 105 yrs. The decrease of disk emission also occurs over a range of wavelengths, indicating that the dispersal must occur almost simultaneously throughout the disk. The disk dispersal phase is quite poorly understood. Viscous accretion transports material onto the central star, but the viscous dispersion timescale for the entire disk is in excess of 10 Mys. Photoevaporation by UV and X-ray photons is needed to explain the rapid dispersion of the outer disk.
In this project, we will numerically study the effects of a photoevaporative wind on a dusty disk. Similar work has been conducted by Font et al. (2004) and Alexander et al. (2006) for a gas-only disk. Here we propose to study the effects of photoevaporation on a dust+gas disk using a 3D, two-phase Smoothed Particle Hydrodynamics code. This is particularly important in the inner part of the disk, where the the dust-to-gas ratio is particularly high and the effects of gas drag are strongest. We will study how the dust effects the timescales of photoevaporation and how photoevaporation effects the planet formation process.
Supervisors: Prof. Jeremy Mould & Dr. Heath Jones (Monash University)
| The standard Tully Fisher scaling relation for spiral galaxies ignores the fact that spirals have bulges. If you write the total luminosity of a spiral as the sum of the disk and bulge luminosities, and if these components each obey fourth power laws in their dynamical velocities, then one expects the fourth root of the sum of W^4 and sigma^4 to be a better velocity parameter, where W is the 21 cm velocity width and sigma is the central velocity dispersion. Semianalytic models show this to be the case. Literature tests of this prediction on data are indicative, but not decisive. More high quality data are required. In hierarchical galaxy formation models, the relative contributions of sigma and W depend on the mass accretion history of the galaxy, which determines the mass distribution of the dynamical components such as disk, bulge and dark matter halo. The wide variety of histories that originate from hierarchical mass assembly produce a wide range of sigma/W for any value of W, which reaches higher values in more bulge-dominated systems. Is this a signature of merger history? |
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Supervisor: A.Prof. Sarah Maddison Infrared and sub-millimetre observations of dusty debris disks around young main sequence stars often show asymmetries which could be due to the perturbing force of an unseen planet, and recent optical and near-infrared images of these disks have started to find planets. Using a modified N-body code, you will use numerical simulations to study the effects of embedded planet(s) in debris disks and a radiative transfer code to make synthetic observations of what telescopes like ALMA will be able to see. Your best planet predictions may soon be realised by direct observations of extrasolar planets as in the case of Fomalhaut and beta Pictoris! You may also join an observational campaign to study the dust content of debris disks. |
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Supervisor: A.Prof. Chris Blake
The large-scale network of galaxies which fills the cosmos, consisting of clusters, filaments, sheets and voids, encodes a great deal of information about the composition of the Universe and the gravitational forces which shaped its evolution. In this project we will explore new ways to quantify this information to learn about the cosmological model, including the effects of dark matter and dark energy. We will focus in particular on the distribution of voids and superclusters, the phases of the underlying Fourier modes, topological statistics such as the connectedness of the galaxy distribution, and reconstruction/transformations of the density field. The project will utilize both large scale N-body simulations generated by supercomputers, and the latest observational datasets from galaxy redshift surveys such as the WiggleZ Dark Energy Survey. The result will be a new and insightful description of the galaxy distribution, and independent tests of the cosmological model.
A scholarship is available to work specifically with A.Prof. Chris Blake commencing in 2012.
Supervisors: Prof. Matthew Bailes, Dr. Willem van Straten & Dr. Simon Johnston (CSIRO)
Swinburne is a founding partner of the High Time Resolution Universe survey for pulsars and fast transients. To date the survey has already discovered over 100 pulsars, including a magnetar, 27 recycled pulsars and over 80 normal pulsars and 20 RRATs. This rich petabyte resource is a goldmine for discovery, and was responsible for the discovery of the celebrated "Diamond Planet". A student is required to help harvest this survey for new riches, including RRATs, timing the binary and recycled pulsars, and following up the expected 500 pulsars the survey will ultimately discover. The student would work closely with staff, postdocs and students from the CSIRO, Manchester, the MPIfR and Cagliari. Strong computing skills are beneficial.
A new supercomputer at Swinburne (the Gstar) has over 100 Teraflops of computing power and a 1.7 PB disk to aid in the processing of these data. A real-time interference rejection system at Parkes and a 400 MHz baseband recorder allow any student with a bent for observations to come up with novel sub-projects.
Supervisors: Prof. Jeremy Mould, Dr. Peter McGregor (ANU) & Michael Brown (Monash University)
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Several lines of evidence indicate that radio galaxies
harbour a heavily extincted Active Galactic
Nucleus. According to AGN unification schemes, the black
hole is hidden by an optically and geometrically thick dust
torus. Near-IR observations using long slit spectroscopy
with adaptive optics (AO) have shown that the ratio of
atomic to molecular hydrogen varies dramatically with
position across the nuclear regions. The molecular hydrogen
is likely shielded from the continuum source on either side
of the torus, leading to higher molecular-to-atomic hydrogen
ratios in these regions. Observations thus allow one to set
upper limits to the physical size of the torus. Keck IFU
observations using OSIRIS with laser guide star AO and
Gemini observations using NIFS will enable the study of a
complete sample of nearby radio galaxies. These data will
allow us to build a full picture of the kinematics and
distribution of the gas around the nucleus, and to trace the
two-dimensional structure of the torus in these galaxies.
Measurements of the emission-line fluxes and profiles ([PII]1.19um, [FeII]1.26um, Pa-beta and H2 2.12um), will lead to maps for the gas centroid velocity, velocity dispersion, as well as channel maps. The velocity fields for all emission lines will be analyzed in terms of a rotation pattern distorted by the presence of two structures: (i) a compact rotating disc; (ii) outflows along the radio jet. A gas mass for the disc will be estimated. Is the nuclear disc being fed by gas coming from the outer regions ? A mass-outflow rate in ionized gas will be measured from [FeII] lines. Palomar 200 inch and KPNO Mayall telescope observing are involved in filtering objects for this project. |
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Unveiling the dark halos of elliptical galaxies Supervisor: Prof. Duncan Forbes The halos of elliptical galaxies have been poorly probed to date and yet they contain the vast bulk of a galaxy's dark matter. Using telescopes such as the Keck 10m and Subaru 8m located in Hawaii, and the Hubble Space Telescope, this project will obtain new dynamical and chemical information for nearby ellipticals. Galaxy and globular cluster data will be used to constrain the dark matter content of the host galaxy and to better understand galaxy formation processes. Skills in imaging and spectroscopy with large telescopes will be acquired. The project is likely to involve collaboration with colleagues based in California. |
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