PhD Projects

Gas giants are the most spectacular outcomes of planet formation, yet their origins are poorly understood. They are massive enough to impact the properties of their parent formation environment, changing its composition and preventing some material from accreting onto their host stars. The GAIA mission will shortly unveil the first significant population of distant gas giant exoplanets, similar to Jupiter and Saturn in our solar system, where signatures of the chemical changes forming planets induce will be encoded in their host star's composition. This project will involve modelling gas giant planet formation to interpret the GAIA exoplanet population. 

The Simons Observatory, in addition to producing new results on the cosmic microwave background, will also produce a millimetre wave survey over 40% of the sky reaching sensitivity levels never before seen. This represents a huge new resource for mm astronomy and will find, among other types of source, high redshift DSFGs, lensed DSFGs, groups and clusters of DSFGs, as well as cool and polarized dust in local galaxies. Perhaps the most interesting aspect of this survey is the ability to detect transient mm sources, including gamma ray bursts, tidal disruption events, supernovae, accreting protostars and flaring stars, as well as other poorly understood phenomena. This project involves working with the SO sources and transients data as it arrives, conducting followup observations of both sources and transients, and comparing these results to relevant models so as to understand the various phenomena better. This work will be undertaken as part of the SO and SO:UK projects.

Overwhelming evidence, from the Universe’s first light (cosmic microwave background) to the Milky Way, shows that most of the Universe’s mass is invisible dark matter (DM). One of the most pressing challenges in physics is identifying the fundamental constituents of dark matter. We are about to enter a new observational era in cosmology where we will be able to answer long-standing questions about the nature of dark matter. The Vera C. Rubin Observatory is a ten-year telescope survey from the mountains of Chile starting this year -- wider, deeper and faster than anything before it -- that will map the distribution of galaxies in the Universe and the distribution of stars within the Milky Way with unprecedented volume, precision and accuracy. In this project, the PhD student will work at the cutting-edge interface of theory, observation and machine learning to lead the search for the gravitational signatures of different fundamental dark matter models. Depending on the interests of the student, it is anticipated that they will work on multiple aspects of: building robust theoretical predictions for the effect of different DM models on the cosmic web of galaxies and stars (e.g., running cosmological simulations); leading the search for these signatures in data from Rubin and complementary photometric and spectroscopic surveys (e.g., Lyman-alpha forest, Milky Way stellar streams, galaxy weak gravitational lensing); and developing machine learning methods to improve the reliability and power of these searches (e.g., graph neural networks, physics informed neural networks).

Exquisite data from experiments such as Euclid, LSST and Simons Observatory deserve optimal analysis.  We have developed a sophisticated Bayesian Hierarchical Model for dealing with cosmological data, principally for weak lensing, large-scale structure  and the CMB, and this project will extend to new science areas such as 21cm cosmology, and include astrophysical foregrounds and instrumental systematics.

The Universe might not be isotropic on the largest scale, and one explanation might be an interesting topology, which is distinct from its geometry.  Analyzing data in the presence of possible anisotropy requires dealing with millions of numbers (correlation matrix) instead of thousands (power spectrum. This project will address the theoretical, statistical, and computational challenges associated with anisotropic models in general, and topology in particular.  The focus is on upcoming datasets: LiteBIRD (CMB), and Euclid/LSST/SKA/… (large-scale structure).

We are now entering an era where studying exoplanet atmospheres in detail is technically feasible. Processes such as their climate, dynamics and escape into space are all possible to study for the first time. In this project, you will support observational programs to study exoplanet atmospheres by developing models to match the observations. In particular, you will support the STELa program on the Hubble Space Telescope, the largest-ever single award of telescope time to study exoplanets. 

Stellar magnetic activity introduces uncertainties and biases in the determination of exoplanet parameters. Being able to disentangle the stellar from the planetary signal is thus critical if we want to study exoplanets. Determining the level of activity is not easy, however, as this has to be inferred from indirect tracers, such as spectroscopic and photometric variability. The aim of this project is to model spectroscopic and photometric variability starting from existing  (magneto-convection) models of stellar surfaces that include the effects of magnetic fields representing a range of activity levels, and to test these models against observations of planet-hosting stars. 

The plethora of extra-solar planets discovered around stars of different spectral type, age and metallicity has undeniably taught us that the planet formation process is ubiquitous and efficient. Perhaps the most puzzling result is that the typical planetary system found is totally different from our Solar System. To better understand the elusive question of how planets form and evolve, one needs to decipher the properties of their natal environments: the "protoplanetary disks". In recent years, the advent of new facilities such as JWST, ALMA, SPHERE/VLT, or VLA has provided revolutionary observations of these environments. Although these observations offer a unique perspective into the planet formation process, there is yet to be a clear consensus of how to interpret them. This is due to many outstanding gaps in our knowledge regarding the complex and interdependent physico-chemical processes responsible for how the gas and dust content of the protoplanetary disks form, evolve and interact to eventually become fully-fledged planets. In this project, you will develop theoretical models, use numerical methods, and build computer simulations to capture the formation and long-term evolution of protoplanetary disks. By simultaneously leveraging the state-of-the-art observations of these disks and extra-solar planets, you will test the predictions inferred from your models to tackle the open theoretical problems of planet formation. You will be free to develop the research direction of the project depending on your own interests.

This project will focus on understanding the combined evolution of exoplanet interiors and atmospheres, with a view to understanding their long-term evolution and properties, and ultimately habitability. We will examine various initial planetary masses and interior and atmospheric compositions, and study how the latter evolve under the combination of e.g., interior thermal and chemical evolution, outgassing from the interior, atmosphere-interior interactions at the surface (e.g., surface chemistry), atmospheric photochemistry and atmospheric evaporation. The student will build upon and extend existing in-house interior and atmosphere codes. The successful candidate will have a strong background in undergraduate physics, including a solid understanding of undergraduate-level hydrodynamics, and good programming skills (e.g., in python). Any additional background in geophysics / atmospheric physics / chemistry is a bonus (but not strictly required). 

Over the last 30 years 5500 extrasolar planets have been found orbiting stars beyond our solar system, with the vast majority orbiting extremely close to their host stars. These discoveries have fundamentally challenged our understanding of planet formation and evolution. Theory predicts that an exoplanet’s atmospheric composition depends on how and where the planet formed and that the extreme radiation suffered by close-in exoplanets leads to strong atmospheric winds and atmospheric loss. To robustly test these theories requires observations of the planets with the largest signals, “hot Jupiters”, which will pave the way for future observations of Earth-sized exoplanets. This project will combine the revolutionary sensitivity of the James Webb Space Telescope (JWST) with Hubble and ground-based data to measure the chemical compositions of hot Jupiters in unprecedented detail. In doing so, the project will perform robust tests of how and why hot Jupiters came to be and how their atmospheres respond to extreme irradiation.

New observations of dust polarization in nearby dusty star forming galaxies (DSFGs) will examine the role of magnetic fields in boosting the star formation efficiency in these objects. These polarization measurements will be compared to evolutionary indicators for the galaxies to determine how the magnetic fields change with time and are affected by the galaxy mergers that trigger their starbursts and, in many cases, AGN activity. Comparison to polarization observations of lower luminosity systems will investigate magnetic fields in progenitor galaxies, while comparison to models will allow us to test theoretical predictions. This work may contribute to the science case and other preparations for the NASA PRIMA mission.

The role of dusty star forming galaxies in the overall history of galaxy formation is currently unclear. They may have significant roles in the overall star formation history of the universe and might also play roles in the formation of galaxies in clusters, protoclusters and as precursors to quasars. This project will make use of the deepest far-IR image ever obtained - the Herschel Dark Field - alongside complementary observations to study the role and evolution of DSFGs over cosmic time. This will include using colour selection to find high redshift DSFGs, conducting followup observations, and comparing your results to theoretical models. This work may contribute to the science case and other preparations for the NASA PRIMA mission.

• Theoretical Topics in Exoplanet Atmosphere - Dr James Owen
• Finding the most distant quasars with Euclid - Professor Daniel Mortlock
• Disentangling stellar and planetary signals in exoplanet transits - Dr Yvonne Unruh
• Accurate cosmology with the Rubin LSST - Dr Boris Leistedt
• Planet formation in the inner regions of protoplanetary discs - Subhanjoy Mohanty
• Confronting the theory of exoplanet evolution with observations - James Kirk
• Dusty star-forming galaxies near and far - Dr Dave Clements
• Exoplanets origins and evolution - Dr James Owen
• Accretion discs around polluted white dwarfs - Dr Chris Manser and Dr James Owen
• Atmospheres of Habitable Zone Exoplanets around M dwarfs - Dr Subhanjoy Mohanty
• Epoch of Reionization with REACH and SKA - Dr Jonathan Pritchard 
• Cosmology with the CMB - Prof Andrew Jaffe and Prof Alan Heavens
• The most luminous galaxies in the local Universe - Dr Dave Clements
• Astrophysics and cosmology from the 21cm line - Dr Jonathan Pritchard
• Cosmology with the next generation of CMB experiments - Prof Andrew Jaffe
• Planet formation and habitability - Dr Subu Mohanty
• The first quasars and supermassive Black Holes - Dr Daniel Mortlock
• Bayesian Analysis of the dynamic Universe - Dr Florent Leclercq and Prof Alan Heavens
• Bayesian analysis of weak gravitational lensing - Prof Alan Heavens and Prof Andrew Jaffe
• Searching for the most distant quasars - Dr Daniel Mortlock
• Higgs, Dark Matter and the Global Search for Physics beyond the Standard Model - Dr Pat Scott
• Direct Detection of Dark Matter and Global Fits - Prof Roberto Trotta
• Cosmology and Fundamental Physics with Euclid - Prof Roberto Trotta
• Extreme Dusty Star-Forming Galaxies - Dr Dave Clements
• The Nature and Evolution of 70 micron selected galaxies - Dr Dave Clements
• The X-ray-Starburst Connection in the Herschel Era - Dr Dave Clements
• Advanced statistical methods for astrophysical probes of dark energy - Prof Roberto Trotta
• The early Universe and cosmological parameters from the Cosmic Microwave Background, Gravitational Waves, and other observations - Professor Andrew Jaffe
• Determining the topology of the Universe from the Cosmic Microwave Background - Professor Andrew Jaffe
• Accretion Disks, Planet Formation and Habitability Around Red and Brown Dwarfs - Dr Subu Mohanty
• Towards optimal statistics of reionization a5 Emulating radiation from variable stars - Dr Yvonne Unruh nd the 21 cm signal - Dr Jonathan Pritchard
• Cool pre-main sequence stars: their surfaces and circumstellar environments - Dr Yvonne Unruh
• Understanding solar brightness changes on climate-relevant time scales - Dr Yvonne Unruh
• Gravitational lensing, dark matter, and black holes - Professor Steve Warren
•  The most luminous galaxies in the local Universe - Dr Dave Clements
• Pushing the limits of high-z LSS structure cosmology - Dr Boris Leistedt
•  Emulating radiation from variable stars - Dr Yvonne Unruh
• Cosmology with likelihood-free inference - Prof Alan Heavens
•  The highest redshift quasars - Professor Stephen Warren
• Planet Formation in the Inner Disc-The First End to End Model - Dr Subu Mohanty
• Stellar Brightness Variability and Exoplanets – Dr Yvonne Unruh
• The Earliest Stages of Planet Formation - Dr Richard Booth
• Molecules in the Atmosphere of Venus - Dr David Clements and Dr Ingo Mueller