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Resolving Galaxy Evolution


In this project we aim to answer some of the outstanding questions in the physics of galaxy formation by using a newly developed instrument, the Sydney-AAO Multi-object Integral field spectrograph (SAMI). We will obtain spatially resolved spectroscopy of thousands of galaxies and then carry out detailed comparisons to the latest and most detailed numerical models for galaxy formation.


Professor Scott Croom.

Research location

School of Physics

Program type



The overwhelming difficulty in understanding galaxy formation is the complexity of baryonic physics, with multi-phase gas, star formation, dust, supernovae, super-massive black holes etc. all influencing the outcome of the galaxy formation process. The multi-parameter nature of galaxy formation has meant that much progress has been made over the last decade by conducting massively multiplexed surveys, allowing samples of up to one million galaxies to be constructed. These have, in turn, allowed detailed statistical analyses to be made, where the correlation between the multitudes of physical parameters can be studied.

All of these major surveys use a single optical fibre to collect the light from each galaxy. Yet, galaxies are intrinsically complex, multi-component systems with multiple structural components (e.g. disks, bulges, halos) and elaborate interactions between the dark matter, stars, gas and super-massive black holes they contain. The use of single apertures thus loses valuable information and adds confusing biases.

In this project we will address many of the most pressing current issues in galaxy evolution, by carrying out large-scale studies providing resolved maps of galaxy emission. Such samples have the potential to profoundly impact the field of galaxy formation by addressing the physical processes at work. These lie in three key areas:

•    How does a galaxy’s environment influence its evolution?  Galaxies have very different properties, depending on whether they lie in high-density clusters or more rarified void regions.  By studying the internal motions of gas and stars, as well as the spatial distribution of star formation within galaxies, we can directly tackle the question of how environment modulates galaxy formation.
•    How does gas get into and out of galaxies?  The formation of stars depends critically on the supply of gas (the fuel for star formation) within a galaxy.  By studying the distribution, motion, chemical composition and ionization state of the gas we will be able to find when galaxies are most efficiently fuelled and when feedback from supernovae or black holes drives gas out of galaxies.
•    How is mass and angular momentum built up in galaxies?  By measuring internal galaxy motions we can estimate galaxy masses and determine which galaxies form from mergers (typically dispersion dominated) or smoother accretion (typically rotation dominated).  The distribution of galaxy spins in voids, filaments and clusters is a powerful probe of how galaxies acquire their angular momentum as a consequence of early tidal torques.

This project will make use of the new Sydney-AAO MOS IFU (SAMI) instrument to build a survey of thousands of spatially resolved galaxies.  This is a major Australian and international project. The questions above, and related issues, allow for a wide range of potential research projects.

Additional information

HDR Inherent Requirements

In addition to the academic requirements set out in the Science Postgraduate Handbook, you may be required to satisfy a number of inherent requirements to complete this degree. Example of inherent requirement may include:

- Confidential disclosure and registration of a disability that may hinder your performance in your degree;
- Confidential disclosure of a pre-existing or current medical condition that may hinder your performance in your degree (e.g. heart disease, pace-maker, significant immune suppression, diabetes, vertigo, etc.);
- Ability to perform independently and/or with minimal supervision;
- Ability to undertake certain physical tasks (e.g. heavy lifting);
- Ability to undertake observatory, sensory and communication tasks;
- Ability to spend time at remote sites (e.g. One Tree Island, Narrabri and Camden);
- Ability to work in confined spaces or at heights;
- Ability to operate heavy machinery (e.g. farming equipment);
- Hold or acquire an Australian driver’s licence;
- Hold a current scuba diving license;
- Hold a current Working with Children Check;
- Meet initial and ongoing immunisation requirements (e.g. Q-Fever, Vaccinia virus, Hepatitis, etc.)

You must consult with your nominated supervisor regarding any identified inherent requirements before completing your application.

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Opportunity ID

The opportunity ID for this research opportunity is 1593

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