Galaxy Formation & Evolution PhD Projects
Research projects on offer in our Galaxy Formation & Evolution group:
The spatially-resolved star formation properties of galaxies across cosmic time
Current studies of star formation at high redshifts are almost ubiquitously based on the ultraviolet continuum emission. However, this is heavily affected by dust extinction, giving us a biased view of star formation activity at early cosmic epochs. While alternative indicators of star formation exist, until now these have been limited in both sensitivity and angular resolution, restricting resolved studies at higher redshifts to only the most extreme systems. The goal of this Ph.D. project is to use kpc-scale observations from two transformational new surveys to overcome these shortcomings, mapping out the star formation in a dust-independent manner within large samples of star-forming galaxies out to the highest redshifts; we will thus trace the physical processes which drive star formation in galaxies across cosmic time, and those which cause it to cease.
The two new surveys, both Edinburgh-led, are: (1) 'JELS' (the JWST Emission Line Survey), which is using deep narrow-band imaging on JWST to observe (and resolve) samples of typical star-forming galaxies back to the highest redshifts (z>6), using their H-alpha emission line; and (2) the 'LoTSS Deep Fields', which is a recently-completed uniquely deep radio survey with LOFAR over the best-studied extragalactic fields, offering the volume and sensitivity to trace the rarer starbursting galaxies across cosmic time, along with the angular resolution to resolve them. The radio data are expected to be further enhanced over 2025-2026 by the 'LOFAR Ultra-Deep Observation' (LUDO), which would be the deepest radio observation ever taken.
The Ph.D. will build on these two observational datasets and follow-up observations. There is a wide scope of possible work, and the precise path to be followed can depend on the interests of the student.
Studying the early history of massive galaxies with JWST and MOONS
Since its launch in December 2022, the James Webb Space Telescope has driven a revolution in our understanding of the beginnings of galaxy formation in the Universe. We now know that galaxies were already forming as little as 300 million years after the Big Bang, with the discovery of proto-galaxies out to redshift, z=13. We have also witnessed the growth of these initial seeds into the first massive galaxies around the end of the first billion years (z~6-8), and even the early onset of quenching processes that shut down star formation in massive galaxies, leading to the first quiescent galaxies by the start of the second billion years (z~4-5).
Not only does JWST provide the unprecedentedly deep infrared imaging necessary to detect these very early galaxies, it also has far-reaching spectroscopic capabilities that will now allow us to study their properties in huge detail, as has only been previously possible for present-day galaxies in the very nearby Universe. In particular, the study of the star-formation histories and metal contents of early galaxies is now possible for the first time, promising far deeper insights into how these systems formed and evolved.
Our extragalactic group in Edinburgh has been highly successful both in winning observing time on JWST during its first two years and in analysing the large public datasets that have been made available to the community. In particular, the large Cycle 1 imaging survey PRIMER (PI: Dunlop) and Cycle 2 spectroscopic survey EXCELS (PI: Carnall) are both led by our group. The successful applicant will have the opportunity to work with these early JWST datasets to study the early evolution of the most massive galaxies.
Our high-redshift extragalactic group possesses a wealth of expertise, spread across 4 faculty members, 4 postdocs and 3 PhD students, spanning all aspects of extragalactic astronomical data analysis. The successful applicant will collaborate with and receive support from this wider group, as well as two new postdocs I will hire in 2024-25. Our group also plays a leading role in the 200-night MOONRISE guaranteed time programme on the upcoming Multi-Object Optical and Near-Infrared Spectrograph (MOONS) for the European Southern Observatory Very Large Telescope, currently under construction in Edinburgh. The student will also have the opportunity to become involved in this project as their PhD progresses.
Relevant links:
Paper describing some of our JWST Cycle 1 spectroscopic results
The PRIMER JWST Cycle 1 programme
The EXCELS JWST Cycle 2 programme
Bridging the mass gap from the first stars to the first galaxies
Sadegh Khochfar and Britton Smith
- Video: Mind the Gap
- The launch of the James-Webb Space Telescope (JWST) has opened a unique window into the high-redshift Universe (z > 6). This PhD project aims at conducting the first physics-rich high-resolution simulation campaign of that epoch, that bridges the mass gap from mini-haloes to massive haloes and includes a self-consistent Lyman-Werner radiation back ground field as well. These new beyond the-state-of-the-art simulations are crucial to provide testable predictions and physical interpretations for observations and to address in particular open questions regarding the formation of the first stars and galaxies. The student will work closely with observational groups in Edinburgh and Japan making use of the latest observations with JWST and ALMA. As part of the project the student will learn to run their own cosmological simulations on compute clusters and analyse them. Python and or coding knowledge is a plus for the project. This project is part of an international collaboration and the student will have the opportunity to work and visit researchers in Germany, Spain, Italy and Japan.
The launch of the James-Webb Space Telescope (JWST) has opened a unique window into the high-redshift Universe (z > 6). This PhD project aims at conducting the first physics-rich high-resolution simulation campaign of that epoch, that bridges the mass gap from mini-haloes to massive haloes and includes a self-consistent Lyman-Werner radiation background field as well. These new beyond the-state-of-the-art simulations are crucial to provide testable predictions and physical interpretations for observations and to address in particular open questions regarding the formation of the first stars and galaxies.
The student will work closely with observational groups in Edinburgh and Japan making use of the latest observations with JWST and ALMA.
As part of the project, the student will learn to run their own cosmological simulations on compute clusters and analyse them. Python and or coding knowledge is a plus for the project. This project is part of an international collaboration and the student will have the opportunity to work and visit researchers in Germany, Spain, Italy, and Japan.
Children of the Cosmic Web: The Birth and Growth of super-massive black holes
- Video: BH project PhD
- Super-massive black holes with masses of one Billion solar masses are observed at the centres of a large variety of galaxies in the local Universe and even as early as 1 Billion years after the Big Bang. While progress has been achieved in e.g. understanding the co-evolution of black holes and their hosting galaxies in terms of self-regulated feedback from accreting black holes we still do not know the physical origin of black hole seeds. In this project the student will focus on seeding black holes in cosmological simulations using the latest discussed seeding models in the literature as well as a newly proposed mechanism to seed black holes in the Universe. The latter assumes the formation of seed black holes at the crossings of the cosmic web, a natural consequence of the hierarchical structure formation paradigm. Equipped with these new simulations the student will predict black hole demographics and properties of the black hole population. Results from this work will be directly complementary and relevant to the James Webb Space-Telescope (JWST) as they provide testable predictions, interpretation and direction for future observational campaigns. As part of the project the student will learn to run their own cosmological simulations on compute clusters and analyse them. Python and or coding knowledge is a plus for the project.
Super-massive black holes with masses of one Billion solar masses are observed at the centres of a large variety of galaxies in the local Universe and even as early as 1 Billion years after the Big Bang. While progress has been achieved in e.g. understanding the co-evolution of black holes and their hosting galaxies in terms of self-regulated feedback from accreting black holes we still do not know the physical origin of black hole seeds.
In this project the student will focus on seeding black holes in cosmological simulations using the latest discussed seeding models in the literature as well as a newly proposed mechanism to seed black holes in the Universe. The latter assumes the formation of seed black holes at the crossings of the cosmic web, a natural consequence of the hierarchical structure formation paradigm. Equipped with these new simulations the student will predict black hole demographics and properties of the black hole population. Results from this work will be directly complementary and relevant to the James Webb Space Telescope (JWST) as they provide testable predictions, interpretation, and direction for future observational campaigns.
As part of the project, the student will learn to run their own cosmological simulations on compute clusters and analyse them. Python and or coding knowledge is a plus for the project.
Machine Learning Galaxy Formation
- Video: Sadegh Khochfar
- PhD Project 2022
In this project, we want to develop new machine-learning algorithms to investigate galaxy formation in the Universe. The algorithms will be applied to numerical simulations of galaxy formation in a first step and then used on observations. The idea is to break degeneracies between simulations and models used in the community and to identify the most important astrophysical drivers of galaxy formation. The student would work with data sets available in the group and from international collaborations.
Unveiling the stellar populations of the first galaxies with JWST
Derek McLeod and Fergus Cullen
With the advent of the James Webb Space Telescope (JWST), we have already seen remarkable progress in our understanding of the demographics of the galaxy population to redshift z=11, roughly 400 Myr after the Big Bang. Early JWST studies have not only demonstrated significant star formation taking place at z > 11 but also suggested a transition towards dust-free stellar populations at this epoch, evidenced by ultra-steep UV spectral slopes. Such steep UV slopes can only be produced by stellar populations free of dust and suggest that we are beginning to probe an era just after the first galaxies have been established. Tantalisingly, we may soon be able to observe the first, truly primordial, galaxies.
The overarching goal of the PhD is to exploit the remarkable power of JWST to build upon these early studies and complete our understanding of the stellar populations of high-redshift galaxies from cosmic dawn to the end of reionization. Our team in Edinburgh is at the forefront of these studies, and the new PhD student will be involved in analysing data for a large range of imaging datasets to trace the evolution of the galaxy population from the end of reionization (z=6) to the earliest epochs of galaxy formation (z > 11). We have also been successful in obtaining large spectroscopic programmes (> 70 hours) to study the galaxy population in greater detail, and the student will be involved in planning future imaging and spectroscopic proposals in JWST Cycle 4 and beyond. This PhD project will be primarily observational in nature, but comparison with the predictions of galaxy-formation theorists/simulators (both here in Edinburgh or elsewhere) will also be of crucial importance.
Under the Computational Astrophysics projects see also:
- A new cosmological residual distribution hydrodynamical solver -Sadegh Khochfar
Under the Milky Way & Local Universe projects see also:
- Galactic Archaeology of Local Volume Galaxies with Euclid -Annette Ferguson