Compact Objects and Time Domain Astronomy
The School of Physics and Astronomy at the University of Southampton offers postgraduate studies (Ph.D.) in a variety of fields in astronomy and space science, including observational and theoretical astrophysics of our own and other galaxies, as well as the study of planetary magnetospheres. We also have a strong interest in high-energy, space-based astrophysics in general and in particular in the major gamma-ray satellite INTEGRAL.
Possible research topics are generally outlined by the research interests of our members of staff. If you have any questions about any particular topic you are welcome to contact people directly. Prof Francesco Shankar would be glad to respond to any (in)formal enquiries.
Have a look at the astronomy group's home page to find out more on what we do here. More general information on postgraduate work in the Physics and Astronomy department at Southampton is available. For more information about the University and its surroundings, look at the University home page.
At the University of Southampton, we value diversity and equality. Both the University of Southampton and the School of Physics and Astronomy are proud to hold Athena Swan Silver Awards. To find out more about our commitment to Equity, Diversity and Inclusion see here.
Several PhD places will be available in the astrophysics group this year, with projects chosen from among those listed below. Candidates need not express a preference for project/supervisor before interviews are held. Applications will be reviewed at the end of January and successful candidates invited for interview shortly afterwards. Late applications may be considered. We also offer the possibility to co-host PhD studentships in collaboration with ESO, Europe’s flagship observatory. PhD projects will typically be supervised by a member of staff of the astro group and one at ESO in Garching near Munich (Germany) or Santiago (Chile). Students will have the opportunity to work two years in an international environment in Germany or Chile before finishing their last year at the University of Southampton. Please contact a member of staff if you are interested.
Scroll down to view the PhD projects available this year
For further information, please contact:Prof Francesco Shankar
Room 5067 (building B46);
School of Physics & Astronomy
University of Southampton
SO17 1BJ, U.K.
How to apply
To apply you will need to get an application form (which asks brief details of your past courses) and the names and addresses of two people who can provide you with a reference (you don't need to upload references yourself, the system will automatically send out a request to the contacts you have provided). The key aspects are (a) what degree course you have done, and any relevant components, especially project work, and (b) your references. Do not worry if you do not know exactly what you want to do. It would be surprising if you did!
If you are interested in applying and would like an application form and further information, please fill in the on-line form, apply to the "PhD Physics" programme, and specify "Astrophysics" in the "Topic of field or research" section to have your application directed to the astronomy group. For part-time research, use this form instead. To apply for the Mayflower Scholarship, use this form.
For more information on how to apply and online application form please visit the University web page.
Quasars are among the brightest lights in our Universe, powered by accretion onto the supermassive black holes that sit at the centres of massive galaxies. Since their discovery in the 1960s quasars have been identified in ever-growing numbers reaching back to the
earliest epochs when the first galaxies in our Universe were forming.
Quasars can be crudely separated from other astronomical sources such as stars and galaxies using multi-colour
imaging data. However, a spectrum is required for unambiguous identification. Quasar
spectra not only enable confirmation of the nature of the source and a measurement of its redshift, but also contain
a wealth of additional information e.g. the widths of the emission lines seen in quasar spectra can be used to
measure the mass of the accreting SMBH that is powering the quasar and the wings of certain emission lines
encode signatures of powerful outflows that could be impacting the quasar host galaxy. The largest sample of
spectroscopically confirmed quasars to date comes from the Sloan Digital Sky Survey (SDSS), which has provided us with hundreds of thousands of quasars out to redshifts of 6 in the northern celestial hemisphere. On account of the bright flux limit and optical wavelength coverage of SDSS however, it is not sensitive to both more distant and obscured quasars. In the former case the optical light is attenuated by dust around the quasar or in the quasar host galaxy while in the latter case it is redshifted into the infrared region of the electromagnetic spectrum.
As part of this PhD project the student will have proprietary access to two new, state-of-the-art spectroscopic survey datasets from the 4MOST spectrograph on the ESO VISTA telescope and the MOONS spectrograph on the Very Large Telescope, which are due to begin observations in ~2021-2022. Together they will allow new parameter space to be probed for quasar discovery and characterisation. 4MOST is capable of probing 2 orders of magnitude deeper than SDSS and MOONS extends into the near infra-red wavelengths where the effects of dust attenuation are much less marked. As a result, they offer an unprecedented opportunity to extend the census of known quasars into the distant and obscured Universe. How many such quasars are out there? How much black hole growth has so far been hidden from our view? Are their properties such as black hole mass, strength of outflows, host galaxy characteristics - similar to or different from the well-established optically selected population from SDSS? This observationally driven project offers several potential avenues of research exploration under the broad umbrella theme of understanding the co-evolution of galaxies and their central supermassive black holes. Which research strand we pursue will largely be driven by the interest of the student and what we discover with our new data.
The Vera C. Rubin Observatory Legacy Survey of Space Time (LSST) will be the premier ground-based imaging survey facility over the next decade. LSST will map the entire Southern sky every 3 days generating petabyte scale datasets containing billions of astronomical sources. Active galaxies with high levels of accretion onto their central supermassive black holes, will be one category of interesting galaxies contained within the enormous LSST dataset. Separating these active galaxies from their inactive counterparts as well as distinguishing them from stars in our own Galaxy, will require us to make use of information about the colours, shapes and variability patterns of LSST sources. It will also be important for LSST to leverage information at other wavelengths e.g. from surveys at infrared, X-ray and radio wavelengths, where active galaxies can have different emission properties relative to their inactive counterparts.
This project will develop new methodologies to combine data from different telescopes to be able to distinguish active galaxies from other astronomical sources as well as infer photometric redshifts based on the colours of these active galaxies. The project will require the student to build up an understanding of the multi-wavelength spectral energy distributions of stars and galaxies in order to design selection strategies to differentiate between them. Given the data volumes that will be generated, the use of machine-learning algorithms will inevitably be necessary to speed up the classification process. This project offers a student the opportunity to get involved in the "big data" challenges currently being confronted by astronomers and will equip the student with a range of skills related to the analysis of large, complex and multi-variate datasets (Image credit: futurism.com).
The aurora is the optical signature of plasma processes occurring in near-Earth space powered by the dynamic interactions between the solar wind and Earth's magnetic field. "Chocolate sauce" is a term which has been informally applied (in particular in the
aurora-zoo citizen science project) to aurora which appears to contain dynamic swirling and flowing motions on small scales (below 5 km). This type of aurora is not clearly structured into typical arcs (curtains), and the motions seem to often change direction, with no apparent relationship to the magnetic field or cardinal points. So far there have been no substantial studies of chocolate sauce aurora, although it is commonly observed above Svalbard, in the high-Arctic, by the University of Southampton's "Auroral Structure and Kinetics" (ASK) multi-spectral imaging system. At such high latitude the nightside geomagnetic field lines map to a region relatively far down Earth's magnetotail. One possibility is that chocolate sauce aurora is an image of magnetohydrodynamic turbulence in the magnetotail plasma sheet, a region of comparatively dense plasma in the equatorial plane of Earth's magnetosphere.
This project will initially test this hypothesis by comparing properties of chocolate sauce aurora with in-situ observations of turbulence made by spacecraft, primarily the Magnetospheric Multiscale (MMS) mission. The overall aims of the project are twofold; to examine the role of turbulence in the loss of energy and particles from the plasma sheet, and to investigate the formation of turbulent motions seen in the aurora. The student will have the opportunity to direct this project according to their strengths and interests, with a flexible balance between observational data analysis, computational modelling, and theory. Machine learning techniques may be applied to output from the Aurora Zoo as a means to rapidly obtain a large set of events for statistical analysis.
A complex system of electric currents flows through Earth's dynamic magnetosphere. A key part of this system is the resistive ionosphere, which acts as a load in the magnetospheric circuit. Although we have built up a large-scale picture of the current flow between the ionosphere and magnetosphere, observations show that the currents are much more structured and dynamic than this large-scale picture can represent. At smaller and smaller scales our understanding becomes increasingly limited, but understanding the small-scale dynamics is key to understanding the physics of magnetosphere-ionosphere coupling. Auroral arcs are a signature of electron (and proton) precipitation into the polar atmosphere. These precipitating charged particles carry part of the magnetic field-aligned current between the magnetosphere and ionosphere, but part is carried by low energy particles which do not produce auroral light. The field-aligned currents close through the ionosphere. This whole system varies rapidly both in time and space.
The aim of this project is to build a detailed 3d model of currents in and around auroral arcs, and to use this model to investigate how the ionospheric conductivity influences the structuring and dynamics of current flow between the magnetosphere and ionosphere. The project will use high-resolution observations of field-aligned currents made by the European Space Agency's "Swarm" mission; a constellation of three satellites which can measure the curl of the magnetic field to infer the field-aligned current density. Ground-based radar and optical observations of the aurora will be used to measure resistive heating of the neutral atmosphere, which can provide an estimate of the altitude profile of current closure through the ionosphere. This combination of state-of-the-art observations and computational modelling will be a powerful tool to advance our understanding of magnetosphere-ionosphere coupling and auroral dynamics.
As matter spirals onto a black hole, it heats up and emits X-rays. The X-rays from this accretion disc encode information about how matter behaves in the region of highly curved space-time. The variability of the radiation is due to a number of noise processes, in addition to which there are - occasionally - Quasi-periodic oscillations (QPOs). The rapid timescales of these QPOs indicate they must be associated with something dynamic or radiative occurring very close to the black hole itself. Whilst QPOs have long been observed from the discs of X-ray binaries harbouring stellar mass black holes, it is only in the last 10 years or so that evidence has emerged that QPOs are also present in active galactic nuclei (AGN), harbouring supermassive black holes (SMBHs). Recent studies have indicated that the presence of QPOs may in fact be much more widespread in AGN that previously thought.
The aims of the project will be to build new methods of locating QPOs in AGN and exploit these to understand the processes creating them. This will entail coding, data analysis and the use of X-ray observational techniques (Image credit: Nature Astronomy).
Our knowledge of neutron stars and black holes in binary systems is a result of observing the X-rays which are produced from the hot accretion disc which forms when the binary components are fairly close to one another. These accreting binaries account for only a tiny fraction of the total number of such systems we should expect to be located in the Milky Way. Locating the non-accreting and wide binaries is important as it can reveal stages of binary evolution (the end product being an in-spiral and merger) otherwise inaccessible to us. However, such systems are extremely hard to locate and new methods are called for.
As a neutron star or black hole transits across the face of its companion star, it acts as a lens and magnifies the apparent brightness of the star. Predictions indicate that many such 'self-lensing' events - created by non-accreting and wide binaries - should be located in data from existing and new optical surveys (e.g. TESS, ZTF and LSST).
The project will entail creating model lightcurves for lensing events, creating a bespoke method for searching for these events (e.g. machine learning) and applying the method to data from new, all-sky surveys (Image credit: thesocietypages.org).
In collaboration with the Indian astronomy centre for excellence IUCAA, we offer exchange opportunities for students to work on novel studies of black holes with state-of-the-art optical and X-ray camera. Students will spend at least 1 year at Southampton and up to 2.5 years at IUCAA in Pune, India, working with members of the Indian space mission for studying black holes, AstroSat, as well as coordinates observations and travelling between UK/India/South Africa/Chile/space telescopes.
Black holes are the most compact objects known. So, physical conditions in their surroundings can change rapidly. The aim of this project is to capture these rapid changes by making state-of-the-art high frame-rate multi-colour 'movies' of black holes in outburst. Observations across the electromagnetic spectrum including X-rays, optical, infrared and radio data are needed to capture the full energy release of black hole emissions both from the accreting material, and from outflowing fast relativistic jets.
You will have the opportunity to plan and execute multiwavelength observations, analyse and interpret the data, and to constrain theories of black hole growth and launching mechanisms for relativistic jets. For more details on this growing field of rapid time domain astronomy, please follow the links below.
Black holes are the densest form of collapsed matter. Understanding these enigmatic objects has implications
not only for extreme physics at energies far beyond what we can create in laboratories,
but also for galaxy evolution and cosmology. Theories of black hole growth suggest that there ought
to be many more active supermassive black holes in neighbouring galaxies than known at present.
We now have new powerful telescopes to find these black holes using X-ray and infrared light.
The e-ROSITA mission will create the most sensitive X-ray maps of the entire sky to-date, and data
from powerful facilities such as NASA's WISE (and soon WFIRST) telescope and Europe's Very Large T
elescope interferometer will be available in the infrared.
This is an ideal opportunity for a PhD student to join revolutionary new telescope surveys with extensive data rights to answer important questions in black hole astrophysics. There will be opportunities to travel to Germany and potentially Chile for observing and data analysis. You will learn big data analysis from very large surveys, and develop expertise in statistical techniques with wide applicability beyond astrophysics.