PhD Studentships in Astrophysics

The Astrophysics Group is offering standard STFC-funded research studentships in astronomy and astrophysics, and we would be pleased to hear from anyone (from the UK or abroad) who is interested in research in these areas. In addition to our PhD studentships, we have a thriving programme for research masters degrees (MSc) for self-funded full or part-time students.

PhD students carry out independent research under the direction of a member of academic staff in one of the group's areas of research interest, and the degree is awarded on the basis of examination of a thesis after three and a half years.

In their first year students may attend advanced undergraduate lecture courses in relevant subjects, and follow courses of directed reading. In all three years postgraduate students are expected to attend the Group seminar series, and to learn presentation skills through giving seminars themselves. Students should also attend the Journal Club, which examines recent research papers of both specialist and more general interest, and relevant Physics colloquia. All students, whether carrying out observational or theoretical research, have the opportunity to visit telescopes abroad to make observations. It is sometimes possible for students to spend a substantial amount of their PhD overseas as guests of another institution where they work with staff who collaborate with the Bristol Astrophysics Group.

The School of Physics at the University of Bristol hosts a vigorous and expanding Astrophysics Group headed by Professor M. Birkinshaw, the Coldrick Professor of Astrophysics and Cosmology. The group conducts research in the general areas of Galactic and extra-galactic astronomy and cosmology, including both theoretical and observational topics. Examples of possible PhD research programmes are given below, along, with links to contact potential supervisors.

XXL: The Ultimate XMM Extragalactic Survey

We are major contributors to XXL, a 50 square-degree X-ray survey, and the largest XMM-Newton science project to date. This survey identifies clusters of galaxies from their X-ray emission and then characterises these systems using a wealth of multi-wavelength data. We use these systems to study the cosmic evolution of both the gaseous intra-cluster medium and of the galaxies that populate these systems. We are interested in how the clusters themselves grow over cosmic time, how the galaxies within them evolve both through time and with the dynamical state of the hosting clusters and how the properties of these systems can be used to constrain our understanding of the Universe as a whole. XXL is enabling the identification of new clusters over a huge range of distance from us, the most distant being seen in light emitted when the Universe was only a quarter its present age. Given this huge time-scale, the survey is ideal for studies of the time-evolution of galaxy clusters.

Group members involved in this programme are Birkinshaw, Bremer and Maughan, and possible PhD projects based on XXL include: the search for the most distant clusters; studying galaxy evolution in clusters; estimating masses of clusters from X-ray data to contrain cosmological models; studying the scaling properties of the clusters and their evolution; observing the Sunyaev-Zel'dovich effect of the clusters. This work will be carried out in collaboration with astronomers around the globe. In certain cases, these collaborations make it possible for PhD research projects to be carried out both in Bristol and in partner institutions. Currently, there is an opportunity to carry out PhD work on the evolution of cluster galaxies jointly between Bristol and the AAO and Macquarie University in Australia.

Exoplanet Formation

Numerical simulations are used to study the formation of extrasolar planetary systems, following the growth of planetesimals into planets. These simulations are also useful in understanding the formation and evolution of our own solar system (Leinhardt).

The Sunyaev-Zel'dovich Effect

The scattering of the microwave background radiation by gas in clusters of galaxies is used to study cluster atmospheres and as a tool to measure the parameters that define the large-scale structure of the Universe. Observations are made using ground-based telescopes in the radio and sub-mm, and compared with X-ray data from satellite observatories. Theoretical aspects of the scattering process are also studied (Birkinshaw).

Observational Cosmology

The investigation of the numbers and properties of faint, distant galaxies can give clues to the processes involved in the formation and evolution of galaxies and as to the overall nature of the Universe itself. Our observational work uses large ground based telescopes as well as data from the Hubble Space Telescope to study the high redshift universe (Bremer).

Accreting Black Holes

At the centre of every galaxy is a super-massive black hole, and in a small fraction of galaxies, called Active Galactic Nuclei (AGN), a significant quantity of gas is flowing into the black hole. This accreting gas forms a disc which emits X-rays that we observe with space-based observatories such as Chandra, XMM-Newton and Suzaku. Detailed modelling of the X-ray spectrum from AGN can tell us about the black hole (e.g., is it spinning?) and the geometry of the X-ray source and disc. There is an opportunity for both theoretical and observational X-ray projects related to black hole accretion flows. In particular, I am interested in looking at the variability characteristics of AGN (e.g., time lags as a function of X-ray energy and Fourier frequency) and how this can be used to "echo map" the inner disc and infer the physics of the accretion flow (Young).

Active Galactic Nuclei and Radio Galaxies

We make use of both satellite and terrestrial observatories to study the physics of active galaxies. The X-ray and radio properties form a particular focus of our work, in which we study the inner geometry and radiation mechanisms as well as the effects of hot gaseous environments on radio-source propagation and evolution. We expect further discoveries from our observing time on the X-ray observatories Chandra and XMM (Worrall).

Cosmology with Galaxy Clusters

X-ray observations of galaxy clusters provide a powerful way to study their properties. We have several programmes underway to study these massive galaxy structures and better understand them. A key goal is to improve our ability to measure the masses of clusters of galaxies - an observational challenge as the systems are dominated by dark matter. Using our improved mass measurements, we aim to test the predictions of different cosmological models against observations of samples of galaxy clusters (Maughan).

Similarity Breaking in Galaxy Clusters

Simple models predict that galaxy clusters should have fractal-like behaviour, with low mass clusters being identical to scaled down versions of high mass clusters. However, observations show that this is not the case. We are studying the scaling properties of clusters to learn about extreme physical processes related to cluster mergers, energy injection from active galaxies, and runaway cooling processes, that are believed to be responsible for breaking expected self-similar scaling (Maughan).

Cluster Lenses

Galaxy clusters act as gravitational lenses, distorting and magnifying the images of background sources. Radio, sub-millimetre and infra-red observations are an efficient way to find new lenses, the study of which will enable us to estimate the mass of the lensing clusters. This provides en excellent way to examine the density structure and masses of these clusters, with a view to understanding the distribution of dark matter and the formation and growth of clusters of galaxies (Birkinshaw, Maughan).

Spectroscopic Surveys

We have a long term observational programme to obtain spectra for complete samples of objects in certain areas of the sky, regardless of their apparent image morphologies. This allows us to investigate, for example, compact dwarf galaxies with no bias due to pre-selection of `likely looking' targets (Phillipps).

Low Surface Brightness Galaxies

The majority of galaxies in clusters are, in fact, small and of low surface brightness. Our programme aims to elucidate the true extent, and properties, of this elusive class of object (Phillipps).

Research in the above areas may be undertaken with any of the members of staff of the Astrophysics Group - follow the links for information about these members of staff and their research.

For further information about the School of Physics or research studentships, or for application materials, please contact Dr Andy Young

  Dr Andy Young
  School of Physics
  University of Bristol
  Tyndall Avenue
  Bristol BS8 1TL
  U.K.

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