Potential Supervisors: Martin Meyer, Richard Dodson, Attila Popping; Research Area: Gas and feedback in galaxies; Data intensive astronomy

Our understanding of the Universe is dominated by studies at optical wavelengths, and the emission from stars.  While such studies have led to huge advances in our understanding of galaxy evolution, they can only reveal part of the picture.  A crucial extra ingredient to study is the material that stars are made of - gas.  The Square Kilometre Array and its pathfinders will lead to huge advances in this field, enabling studies of the emission from neutral atomic hydrogen at much larger distances than ever before.  This project will aim to make use of data from two of the leading deep astronomical surveys currently underway (the CHILES survey being carried out on the Very Large Array in New Mexico, USA, and early science data from the DINGO survey on the Australian Square Kilometre Array Pathfinder) to create some of the most distant images of the atomic hydrogen content of galaxies ever made.  These surveys are highly data intensive, with the data products for DINGO ultimately expected to exceed 1PB in size.  This project will explore new methods to deliver the best possible survey images and refine the pipelines required to analyse data on such a massive scale.  Research work will be carried out on the Galaxy and Magnus supercomputers at Pawsey, along with cutting edge resources available through the Amazon Web Services.  Collaboration with colleagues in the United Kingdom is also expected, with this work directly relevant to the successful delivery of science with the Square Kilometre Array. 

Image: ASKAP (credit CSIRO) 

Potential Supervisors: Martin Meyer, Attila Popping, Simon Driver, Lister Staveley-Smith; Research Area: Gas and feedback in galaxies; Data intensive astronomy, Multi-wavelength and spectroscopic surveys

The era of the Square Kilometre Array presents many exciting challenges.  For large surveys of the sky (be it wide-area studies of the nearby Universe or deep studies looking back in time) one of these challenges is locating the emission from galaxies in the huge amounts of data the next generation of telescopes will deliver.  New algorithms are significantly advancing our abilities to automatically detect and parametrize the signals from astronomical sources, yet a number of important avenues remain unexplored.  This project will investigate new ways in which we can deliver the most complete and accurate galaxy catalogues possible, be that through the use of optical redshift data to provide robust priors on the locations of galaxies, or the development of new methodologies, such as machine learning algorithms, to refine the reliability of automatically generated sources catalogues.  This work is vital to the successful completion of spectral line surveys over the coming decades, in which billions of dollars of radio astronomy research infrastructure is now being developed and for which many millions of galaxies are going to need to be automatically identified and characterised. This project will make use of ASKAP early science data, and that from existing facilities, to make new measurements of the environmental dependence of the HI mass function, gas-fraction scaling relationships, and the cosmic density of HI.

Image: Simulated galaxy distributions from the DINGO and WALLABY surveys on ASKAP, the image cubes from which are expected to contain ~600,000 galaxies. 

Potential Supervisors: Martin Meyer, Danail Obreschkow, Luca Cortese; Research Area: Gas and feedback in galaxies; Multi-wavelength and spectroscopic surveys

The material in galaxies is not at rest.  In the disks of late-type ‘spiral’ galaxies it orbits galactic centres at ~100,000s of kilometres per hour, on top of local turbulent motions and the more radical processes driving material both in, and out of, galactic disks altogether.  The 21cm line of neutral hydrogen is an excellent tracer of these motions, providing unique insight into the dynamical nature of galaxies, their angular momentum, the regulation of galactic structure, and the nature of their hidden dark matter haloes.  This project will align neutral atomic hydrogen data from current and future HI surveys (including ASKAP early science data) with that from cutting edge multi-wavelength datasets (including 3-dimensional optical IFU datasets) to shed new light on galaxy dynamics and help understand how the rich diversity of galactic structures in the Universe came to be.  How has the angular momentum distribution in galaxies changed with time?  What is balance of ordered and random motion?  What drives the redistribution of material within galaxies?  How do the local dynamical properties of galaxies correlate with their environment?

Image: Rotation of NGC2403 captured from HI observations (credit THINGS team)  

Potential Supervisors: Attila Popping, Lister Staveley-Smith, Martin Meyer; Research Area: Gas and feedback in galaxies

The distribution of matter in the Universe is not homogenous, but rather forms a complex web of walls, filaments, groups and clusters.  Galaxies act as trace particles for this complex structure filling the Universe, with the underlying structure being dominated by  Dark Matter and highly ionised gas.  While extremely important for understanding how galaxies were able to grow and continue to form stars over the history of the Universe, this highly ionised material is extremely difficult to observe.  This project will explore new ways of detecting the hidden cosmic web at radio wavelengths, through continuum observations for synchrotron emission, to deep spectral line observations for the small amount of neutral hydrogen still expected to be exist between and around galaxies.  With a view towards future observations with FAST, the five hundred metre aperture telescope nearing completion in China, along with deep future surveys with the MeerKAT Square Kilometre Array pathfinder in South Africa, this project aims to advance our observational limits for one of the most elusive components of the baryonic Universe. 

Image: Simulation of the cosmic web (credit Popping) 

Potential Supervisors: Martin Meyer; Anne Pellerin; Research Area: Gas and feedback in galaxies; Multi-wavelength and spectroscopic surveys

The unparalleled capabilities of the Hubble Space Telescope lets us capture images of nearby galaxies with such exquisite resolution that individual stars can be identified and classified by type.  Using these images, we can gain a much deeper understanding of how massive stars are born, how they leave their stellar nurseries, and the way these stars drive energy into the gas and dust that surrounds them.  This project will use optical images from Hubble, space-based infrared images from Spitzer, and radio wavelength images captured from the ground, to understand the way in which stars are born, how they disperse into the star field background, the connections to their gas content, and the way they heat the interstellar medium.  It is expected the student will spend time in New York state in the US for collaboration purposes. 

Image: HST image of NGC131 (credit NASA, ESO, Pellerin) 

Potential Supervisors: Martin Meyer, Simon Driver, Aaron Robotham; Research Area: Gas and feedback in galaxies; Multi-wavelength and spectroscopic surveys

After the big-bang and recombination, the baryonic `regular’ matter content of the Universe was dominated by the first element on the period table - atomic hydrogen.  Over time, that material has been transformed into stars, galaxies, black holes, and the wealth of other different states of matter we see today.  Indeed today, neutral atomic hydrogen comprises only relatively small part of the total mass budget of the Universe, yet still exists in significant quantities in galaxies, and continues to play a driving role in their evolution.  This project will study the connections between neutral atomic hydrogen (measured in the radio with telescopes such as the Square Kilometre Array and its pathfinders), molecular material (measure through mm observations with the ALMA telescope in CHILE and the ATCA in Australia) and the other major baryonic constituents of galaxies (traced through the rich multi wavelength imaging and spectroscopy of the GAMA survey).  How do the scaling relationships between these quantities evolve?  And most importantly what are the underlying physical processes that drive the evolution of material from one state to another?     Results will be compared to the latest semi-analytic and hydrodynamic simulation runs to assist in this interpretation.

Image: Multi-wavelength images from GAMA (credit GAMA team)

Potential Supervisors: Martin Meyer, Lister Staveley-Smith; Research Area: Gas and feedback in galaxies; Multi-wavelength and spectroscopic surveys

The evolution of galaxies is driven by many - often extreme - physical processes.  Stars explode, supermassive black holes drive vast jets out of galactic centres, galaxies collide and gravitationally harass each other, and vast winds drive material out of galaxies as they fall into the densest regions of space.  One of the most dramatic impact these processes can have is to radically alter the gas content of galaxies. This basic fuel underlies the star formation in all galaxies, and by impacting it, the lives of galaxies can be radically transformed.  This project will look at the importance and impacts of these environmental and feedback processes on the evolution and gas-content of galaxies through neutral hydrogen observations, in combination with multi wavelength data tracing star formation, AGN activity, and environment.  This project will use early science data from ASKAP.

Image: M81 group (courtesy of NRAO/AUI)

Potential Supervisors: Martin Meyer, Attila Popping, Lister Staveley-Smith, Barbara Catinella; Research Area: Gas and feedback in galaxies; Multi-wavelength and spectroscopic surveys

The sheer expanse of the Universe and the dimming of sources with distance presents a significant problem for understanding galaxy evolution, with the emission from increasingly distant objects weakening to the point where they are no longer detectable.  While the Square Kilometre Array pathfinder telescopes in Australia and South Africa will vastly increase our ability to directly detect distant emission from neutral atomic hydrogen, these telescopes will still have limits as to the mass and distance of galaxies they can directly study.  New methods, involving the statistical combination of the signals from many different galaxies together, can provide a powerful new window through which to advance the observational exploration of the Universe, giving us crucial information on how the average properties of galaxies have changed with time.  This project will utilise early science data from the Square Kilometre Array pathfinders (and in particular the DINGO survey on ASKAP), in combination with that from existing facilities, to refine our use of these statistical methods (HI stacking, intensity mapping) and push the boundaries at which we can understand the evolution of this material to the highest redshifts possible. 

Image: Stacking the emission from 10,000s of galaxies with DINGO and ASKAP.