Projects on offer for 2019 entry will be progressively added here in December. The projects themselves may evolve somewhat before October 2019.
Cosmology with the next generation of CMB experiments - Prof Andrew Jaffe
The cosmic microwave background (CMB) gives us a snapshot of the Universe at a small fraction of its present age, when it was hot, dense, and simple. With satellites like Planck, we have measured the intensity of the CMB over most of the sky. The next generation of CMB experiments from the ground and from space will open up new windows on cosmology: further detailed measurements of the polarisation properties of CMB photons will be made over the coming decade, as well as new measurements of the energy spectrum of the CMB and the way it deviates from a perfect black body. Both of these will give us a way to see particles and fields interacting in the early Universe. Working with experimental teams around the world, this project will combine new statistical methods to analyse the data that will become available during the course of this PhD and beyond alongside new theoretical techniques to make predictions of the signatures of early-Universe physics such as inflation.
Bayesian analysis of the dynamic Universe - Dr Florent Leclercq and Prof Alan Heavens
The spectacular progresses of the last decade in observational cosmology have tested the validity of our standard picture of the Universe at unprecedented accuracy. Challenges now arise from studying the inhomogeneities of the cosmic large-scale structure, which may contain a wealth of untamed information on some of main problems facing modern cosmology: the nature of dark energy, the masses of neutrinos, the processes driving cosmic inflation, and the presence of gravitational waves. Ideally, the connection between surveys and cosmological models should be made in a full-scale Bayesian framework, by exploring the multi-million dimensional parameter space. Tackling this idea, several algorithms and software packages have met some success in recent years. This project aims at exploiting these results to further our understanding of cosmology and fundamental physics. The proposed work includes the use of computational techniques to predict and extract physical signals, the application to synthetic and real galaxy and lensing surveys, and the cross-correlation with complementary astronomical data sets. As natural outcomes of the approach, the project will provide unprecedentedly detailed characterisations of the dynamic cosmic web in the local and extreme-scale Universe. Potential applications include inferring the Hubble expansion rate from supernovae, including the derived knowledge of the peculiar velocity distribution; investigating the kinetic Sunyaev-Zel’dovich effect from filaments; exploring correlations between galaxy properties, such as intrinsic alignments, and the matter distribution and tidal fields, to further the understanding of the galaxy formation process.
Exoplanet Origins and Evolution - Dr James Owen
The last decade has seen an explosion of exoplanet detections. We now know most stars host a planetary system; however, these exoplanetary systems are incredibly diverse and unlike our Solar-System. Using the ALMA telescope, we have been able to image the planet-forming environments (protoplanetary discs) at unprecedented resolution and sensitivity. These images have revealed that these protoplanetary discs are being shaped and disrupted by planets forming within them. However, linking the properties of planet-forming discs to the observed exoplanet population remains an unsolved theoretical problem. This project involves building theoretical models of how forming planets will interact with their parent protoplanetary discs and linking them to current observations (see Picture). This project will allow the student to undertake sophisticated hydrodynamical computer simulations of planet formation, and/or become involved in state-of-the-art observations.
Planet formation and Habitability (2 projects) - Dr Subu Mohanty
I'm offering 2 PhD projects on the subject of planet formation and habitability. The interested applicant will have a chance to work on either, or (more likely) a combination of the two. The requirements are that the applicant be proficient in hydrodynamics, and ideally have some experience in magnetohydrodynamics and radiation physics as well (though the latter two are not essential, and can be learnt on the fly). The applicant should have experience in coding, in IDL, Python, C or Fortran. The work involves astrophysical theory and numerical simulations.
The projects are as follows:
1) The Formation of Super-Earths: In this work, we will investigate the formation of Earth and super-Earth mass planets (~1--5 Earth-masses), orbiting in close proximity to the central star. Such planetary systems appear to be extremely common, making up ~50% of all systems, and it is therefore essential to understand their genesis. The work will build upon the theoretical model proposed by our group and collaborators in the US, and will use numerical simulations -- based upon both existing codes and new ones written by the student -- to construct a quantitative model and test its predictions. The goal is to build the first working model of both how these planets form, and why they occur in half the systems and not the other half.
2) Habitability of Earth and super-Earth mass planets in the Habitable Zone around M dwarfs: M dwarfs (commonly known as red dwarfs) make up ~80% of all the stars in our galaxy; it is now also clear that they often harbour rocky planets in their Habitable Zones. They are therefore prime targets in ongoing searches for habitable planets around other stars. However, M dwarfs are also very magnetically active, and the resulting flux of X-ray/UV photons and charged particles from the star can seriously ablate, or even entirely remove, the atmospheres of planets in orbit around them. In this work, we will examine the efficiency of such ablation, and the necessary planetary attributes required to remain habitable in the face of such erosion, for a range of planetary masses, compositions, orbits and atmospheres. It will require theoretical calculations, as well as numerical simulations -- using radiation hydrodynamic codes we have already developed as well as chemical network models that the student will construct based upon existing models. The goal is build a picture of what kinds of planets are expected to be habitable on Gigayear timescales around M dwarfs, and thus provide a roadmap for upcoming ground- and space-based missions dedicated to hunting for habitable planets around M dwarfs.
The first quasars and super-massive black holes - Dr Daniel Mortlock
A quasar, the glowing disk of gas around the super-massive black hole at the centre of a galaxy, can be hundreds of times more luminous than its host galaxy, and the brightest quasars are the most powerful non-transient objects in the Universe. Quasars have been discovered when the Universe was just 5% of its current age (of 13.8 billion years) and represent the only way to trace the formation of the first super-massive black holes. The first part of this project would be to use the results from surveys of distant quasars to determine their properties as a population and, in particular, how it is evolving with cosmic time. This will involve a combination of modelling and Bayesian inference to combine the results of very different samples, hence aiding the design of future surveys that aim to push to even greater distances. The second part of this project concerns the black holes themselves: it is very difficult to explain the formation of black holes of > 10^9 Solar masses in less than a billion years, but another possibility is that they are not actually so massive - their mass estimates come from extrapolating an imperfect empirical correlation established from a different population of quasars which, typically, have much lower mass black holes, and the current approaches to this problem tend to ignore the various sources of uncertainty. In this project we will go back to the original data and establish what can really be said about the first super-massive black holes and quasars and their formation mechanisms.
The Most Luminous Galaxies in the Local Universe - Dr Dave Clements
The most luminous galaxies in the local universe are the Ultraluminous Infrared Galaxies. These were first discovered by IRAS in the mid-80s, but they are still a major target of observational research today, at least partly because they seem to be the local equivalents of the high redshift dusty star forming galaxies being uncovered in unexpected numbers by Herschel. This project aims to deepen our knowledge and understanding of these systems through the use of existing data eg. from Herschel and Akari, and through the acquisition of new data. A key resource for this project will be the HERUS (Herschel ULIRG Survey) dataset on local ULIRGs. Aims for this project include determining the physical environment in the starburst regions powering ULIRGs, seeing what effect these conditions have on massive star formation, fitting spectral energy distribution models to the broad-band spectra of these objects, examination of selection biases that may affect our comparison of local and high redshift populations, and the production of submm spectral line surveys for these objects using archival and, possibly, new observational data.
Young stars in the galaxy - Dr Yvonne Unruh
The WEAVE/SCIP survey will study short-lived stellar-evolution phases
in the Galactic disc. One of the goals is to understand the interaction
between the galactic environment and star formation and evolution.
The survey will result in more than 100000 spectra to be analysed and
classified, and the initial focus of your project will be to develop
methods for automatic spectral classification and the identification of
unusual objects / outliers.
An interest in numerical methods and statistical inference will
Past projects have included:
- Bayesian Analysis of Large-Scale Structure and lensing - Prof Alan Heavens, Prof Andrew Jaffe and Dr Florent Leclercq
- 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 - Dr Roberto Trotta
- Cosmology and Fundamental Physics with Euclid - Dr Roberto Trotta
- The Nature and Evolution of 70 micron selected galaxies - Dr D.L. Clements
- The X-ray-Starburst Connection in the Herschel Era - Dr D.L Clements
- Advanced statistical methods for astrophysical probes of dark energy - Dr R Trotta
- The early Universe and cosmological parameters from the Cosmic Microwave Background, Gravitational Waves, and other observations - Professor A Jaffe
- Determining the topology of the Universe from the Cosmic Microwave Background - Professor A Jaffe
- Accretion Disks, Planet Formation and Habitability Around Red and Brown Dwarfs - Dr S Mohanty
- Towards optimal statistics of reionization and the 21 cm signal - Dr J Pritchard
- Cool pre-main sequence stars: their surfaces and circumstellar environments - Dr Y Unruh
- Understanding solar brightness changes on climate-relevant time scales - Dr Y Unruh
- Gravitational lensing, dark matter, and black holes - Professor S Warren
- Exoplan et origins and evolution - Dr James Owen