Galaxies

Understanding the formation and evolution of galaxies is one of the central missions of extragalactic astronomy. Our planet Earth revolves around the Sun, which in turn is but one star out of hundreds of billions making up our Milky Way Galaxy; to understand galaxies is to appreciate our place in the universe.

Galaxy formation starts with tiny variations of dark matter density in the earliest moments of the universe. Gravitational pull causes regions of higher density to collapse and form the first structures, from the first galaxies to the clusters and superclusters of galaxies that create the large-scale scaffolding of the cosmos.

Hydrogen gas subsequently cooled and settled in the centres of galaxies to form stars. Galaxies are gigantic star factories; over their lifetime they may produce millions to even trillions of stars, each possibly hosting planets. Inside stars, hydrogen gas is converted into carbon, nitrogen, oxygen, and virtually all other elements found in nature.

Through stellar winds and supernova explosions, those elements are strewn into space and recycled into the next generations of stars and planets, and, ultimately, into us. The story of galaxy formation and evolution thus links the two big questions ‘how does the universe begin?' and ‘what are the origins of life in the universe?’.

“Galaxies are the test particles of cosmology - to understand the universe one must first understand galaxies.”

Professor Duncan Forbes , Centre of Astrophysics and Supercomputing

Our researchers are engaged on many different aspects of this problem and from multiple different avenues. Wide-field surveys of galaxies in the nearby universe provide a comprehensive picture of the demographics of the galaxy population in the present day. In contrast, very sensitive ‘pencil beam’ surveys locate the most distant galaxies, observed when the universe was only a few percent of its current age, giving a sense how galaxies grow and evolve over cosmic time.

Detailed studies of individual objects or systems help to understand the processes of formation and disentangle the effects that drive its evolution. All of these insights inform, and are informed by, the latest theoretical models and numerical simulations of galaxy formation and evolution in a cosmological context. 

Did you know?

The billions of galaxies in the universe mostly come in just two basic  types - spirals and ellipticals. Our astronomers are understanding how this came to be from investigations of young galaxies in the early universe, old stars around nearby galaxies and sophisticated computer simulations.

Our researchers use many, if not most, of the world’s leading facilities:

Australian radio telescopes (including ATCA, Parkes and ASKAP) to measure the mass and dynamics of neutral gas in and around galaxies
Spatially resolved spectrographic instruments (including ALMA, KCWI and MUSE) to make detailed maps of star formation, shocks, and gas dynamics within individual galaxies
Multi-object spectrographs (including 2dF, KMOS and 4MOST) to obtain essential distance or redshift information for large galaxy samples
World-leading optical and infrared imaging facilities (including VST, VRO and WISE) to map galaxies over very wide areas
Some of the world’s largest optical or infrared telescopes (Keck, VLT, Gemini,  HST and JWST) to map the galaxies at the edge of the observable universe
Swinburne's own OzSTAR supercomputing facility and the Theoretical Astronomical Observatory to produce, analyse and share the results of massive numerical simulations of galaxies across cosmic time.

Our projects

The universe's first billion years

Using the next generation James Webb space telescope and new machine learning methods, we aim to find rare and unusual galaxies and stars that emerged in the first billion years of cosmic history.

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Galaxy and mass assembly

By combining distance measurements from optical spectroscopy with panchromatic imaging spanning X-ray, ultraviolet, optical, near-to-far infrared and radio wavelengths, census-class galaxy surveys like GAMA, DEVILS and WAVES provide a comprehensive view of the astrophysical processes that shape the lives of galaxies.

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Measuring the masses of galaxies

We are pioneering new experimental approaches to measure the total mass of the dark matter halos that surround galaxies, through the relativistic effect of weak gravitational lensing. By connecting the properties of galaxies to the total mass of their larger dark matter halos, the goal is to derive new insights into how the dark matter influences the formation and evolution of galaxies.

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Galaxy structure

Using in-house software, we are finding and quantifying the structural components of galaxies.

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DUVET Survey

We’re using the faintest spectral features in galaxies to make fundamental constraints on how stars form and impact the galaxy and circumgalactic medium around them.

Understanding ultra diffuse galaxies

Using the Keck Observatory and other 8-10m class telescopes, we are investigating a new class of ultra diffuse galaxies that challenge existing theories for galaxy formation. Their globular cluster systems may hold the key to their understanding.

Swinburne astronomers use the world’s best telescopes, including the Dish at Parkes, to study the properties of galaxies.

DYNAMO galaxy project

DYNAMO is a sample of nearby galaxies that are matched in properties to galaxies of the ancient universe, which we use as laboratories for studying star formation processes.

Globular clusters in extragalactic systems

We are investigating the formation and evolution of globular clusters and their host galaxies. This problem is tackled using high resolution imaging from the Hubble Space Telescope, combined with ground-based imaging and multi-object spectroscopy with the Keck telescopes.

Observational studies of massive black holes

We are establishing the connections between the massive black holes at the centres of galaxies and their host galaxy.

The Taipan galaxy survey

Taipan is a new spectroscopic survey facility at Siding Spring Observatory that has been designed to measure the distances to millions of galaxies across the entire Southern sky in order to construct a comprehensive map of the properties, structure and motion of galaxies in the nearby universe.

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Linking the circumgalactic medium to galaxies

Our Multiphase Galaxy Halos Survey uses both observations and simulations to determine how the CGM influences and drives galaxy evolution.

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The physics of gas flows around galaxies at cosmic noon

We are examining the circumgalactic medium at the universe’s epoch of peak star formation in order to address how the evolution of galaxies is influenced by gas flows.

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The nature of damped Lyman alpha systems

Detecting damped Lyman alpha systems (DLAs) in sightlines to galaxies, as opposed to quasars done previously, is a new approach that will be used by 30m telescopes in the future able to determine the size, mass and kinematics of DLAs for the first time to understand their nature and to perform 3D neutral hydrogen tomography in the early universe.

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Understanding galaxy evolution through HI observations

Using observations from next generation radio telescopes, this project aims to understand the fundamental physical processes affecting galaxy evolution in the local universe including angular momentum, gravitational interactions and hydrodynamical processes.