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The Universe is an incredibly dynamic place. All across the cosmos galaxies are smashing into each other, tearing long plums of material into space and inducing intense bursts of star formation, which shine across the Universe. These `Cosmic Car-Crashes’, known as mergers, are one of the primary mechanisms by which galaxies to grow over time. Smaller sub-units of galaxies combine together to form larger systems, which in turn also merge together to form some of the colossal giants we see today – a process known as hierarchical galaxy formation. Understanding the frequency, location, type and impact of these mergers is paramount to our understanding of galaxy evolution processes and the re-distribution of stars, gas and dust in the Universe.

 

Two Galaxies in the process of merging, as viewed by the Hubble Space Telescope. Credit: NASA

However, to date very little is known about the mergers outside of the local Universe; the end point of the galaxy evolution process. As such, we have very little idea of how this important process is shaping the evolution of galaxies and resulting in the Universe we see today. The reason for this is primarily due to past observational difficulties in accurately measuring the distances to large samples of galaxies outside of the local Universe (a key requirement for tracing galaxy mergers). This has recently changed with the ongoing Deep Extragalactic VIsible Legacy Survey (DEVILS, Davies P.I.). DEVILS is building a spectroscopic sample of ~50,000 galaxies extending out to redshift~1, ideally suited to exploring the impact of mergers on the galaxy population over the last 8 billion years.

Within this project the student will explore the frequency of mergers as a function of other galaxy properties, and their evolution with time, using a number of methods ranging from exploring the close physical separation of pre-merger galaxies, the morphological identification of post-merger systems in high resolution Hubble Space Telescope data, and the statistical reconstruction of merger rates from the evolution of the global galaxy population. These can be used to determine how mergers are impacting the evolution of galaxies. Following this, the results will also be compared to state-of-the-art simulations of galaxy evolution processes, which aim to accurately model the impact of mergers.

New students will join the large international DEVILS team, working with world-leading experts in their field and using cutting edge data to explore some of the most contemporary and high-impact questions in astrophysics today.  The student will also be trained in observational astronomy using large surveys, galaxy evolution science, and rigorous statistical analysis of big data and/or modelling of astrophysical phenomena, galaxy formation and cosmological simulations. The student will also be expected to participate in observing runs at remote telescope locations inside and outside of Australia, gaining a solid foundation in observational astronomy.

Finally, this project will also lay the foundations for future, much larger, studies with the Wide Area VISTA Extragalactic Survey (WAVES) on the, currently under-construction 4MOST telescope, giving the student a unique opportunity to kick-start their research career working on one of the largest astronomy projects of the coming decade.

The Anglo Australian Telescope (AAT), where the DEVILS Survey is currently underway.

 

Potential Supervisors

Dr Luke Davies

Senior Research Fellow

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Professor Simon Driver

Senior Principal Research Fellow

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A/Prof Aaron Robotham

Principal Research Fellow

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