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. Dr Francesco Shankar would be glad to respond to any (in)formal enquiries.
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. Have a look at the astronomy group's home page to find out more on what we do 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 available projects below
For further information, please contact:Dr 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. 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, selecting the "Astrophysics" option to have your request 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.
The Department of Physics and Astronomy (P&A) at the University of Southampton and the fast-growing data science start-up company HAL24K are looking for a highly motivated student to undertake a challenging 4 years PhD project at the University of Southampton. The project will be based at the Department of Physics and Astronomy and is aimed at developing and implementing innovative algorithms to "Big Data" problems, specifically those at the intersection between the future needs of observational Astronomy and the current challenges being tackled by HAL24K (e.g. algorithms for smart cities). Of key interest is the application of deep learning to predict future time-series behaviour and modelling of image time-series. The PhD program will be jointly supervised by a member of the Astronomy Group in the department and a research scientist associated with HAL24K.
The Earth's magnetic field forms a cavity in the solar wind called the magnetosphere; the complex interaction between the solar wind and the magnetosphere produces variations in the intensity of the radiation belts and the most spectacular displays of the aurora. These interactions depend on the orientation of the magnetic field associated with the solar wind (the interplanetary magnetic field, or IMF); a "southward" orientation of the IMF is preferential for many magnetospheric processes, but the IMF direction is highly variable, and the dynamics of the magnetosphere under northward IMF conditions are, in comparison, poorly understood. The aim of this project is to use in situ satellite data from spacecraft such as the European Space Agency's Cluster mission to determine and explain the structure of the magnetotail during the more complex intervals associated with northward IMF. We expect this work will lead to a significant contribution to our understanding of the magnetosphere's response to northward IMF conditions.
The Earth's aurora borealis are a spectacular natural phenomenon, caused by energy deposition from the 'solar wind' into the upper atmosphere through the process of Joule heating. Recent work at Southampton has shown that electric fields on temporal scales of hundreds of milliseconds can be determined by auroral observations made by state-of-the-art instruments. So far, only simple electric field structures have been considered, but more complex parameterizations could quantify spatial variability on scales of hundreds of metres and therefore reveal the true contribution to atmospheric heating made by Joule heating. The project will involve fieldwork on the Arctic archipelago of Svalbard, in order to operate the auroral cameras and supporting ionospheric radars; training will be provided in Arctic survival and safety techniques, and operation of the optical and radar instrumentation.
An exciting opportunity has arisen for a student to work on data from the AstroSat mission - the most sensitive
fast timing multiwavelength space telescope in-orbit. AstroSat was launched by India in 2015 and its operations
are now in full swing. The student will spend at least 1 year at Southampton and up to 2.5 years at IUCAA in Pune,
India, working with AstroSat team members and coordinating multiwavelength observations of outbursting black holes.
Frequent collaboration between UK/India/South Africa/Chile/space telescopes is envisaged.
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 see the following links:
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.
Astronomy is undergoing a revolution. New surveys are regularly scanning the sky and create movies
rather than static images of the sky. This allows us to capture how stars explode or how black holes
accrete mass over time with for large samples of objects.
In Southampton, we are leading VEILS and VOILETTE, infrared and optical time-domain surveys with goals that range from discovering and characterising distant supernovae to mapping the variations in the growth process of supermassive black holes in the centre of galaxies. These variations will be used to reveal the physics at play that lead to the most energetic radiation output in the universe. In addition, we can measure time lags between variations in the optical and infrared and constrain the equation-of-state of the elusive dark energy that fills about 70% of the universe.
As a student on this project, you will take a leading role in the VOILETTE survey. You will be working on the discovery of new transient objects and the identification, classification, and interpretation of variable supermassive black holes. This will involve a large range of skills from data reduction of a large stream of data, machine learning techniques to identify variable sources, to developing physical models to interpret the data. You will be part of an international team with partners across Europe, the Americas, and Asia.
How do black holes grow and how do they influence their host galaxies in the process?
All big galaxies in the universe host a supermassive black hole with millions to billions
of solar masses in their centre. We know now that these black holes are fed by accretion
of mass from their surrounding and that the growth is tightly connected to the evolution
of the host galaxy. However, the exact mechanisms are not fully understood, in part because
the mass accretion takes place on very small spatial scales. The resolution power to see
these processes is equivalent to resolving the distance to the nearest stars of our sun in
galaxies tens of millions of light years away. Since few years, this resolution power is available
in the infrared (IR) by making use of the Very Large Telescope Interferometer (VLTI) at Paranal in
Chile, where up to four 8m-class telescopes are combined to provide the resolution power of a 130m
telescope. Such observations revealed how dusty gas is distributed around the black hole and led
to the discovery of a new dusty wind structure that is responsible for the bulk of the IR emission.
A new instrument, MATISSE, is currently being commissioned at the VLTI, which will enable us to reconstruct first real images of the accreting dust and gas. With this instrument, we will get a first panchromatic view of the accretion and outflow of hot and cold gas. In the course of the PhD project, you will be amongst the first to use this instrument for scientific exploitation. You will be trained on interferometry data reduction and modelling, including further development on radiative transfer models. More on VLTI's impact on active galactic nuclei research here.
Actively growing supermassive black holes are the most energetic objects in the universe. It has
recently become clear that our standard picture of this growth process is incomplete: While it was
considered that the bulk of the dusty gas around the supermassive black hole is distributed in a disk-like
configuration, observations at the highest angular resolution in the infrared showed that significant
mass is associated with a dusty wind streaming away from the black hole environment. This adds to the
known outflows of highly ionised gas that are a common feature in these active galactic nuclei. However,
dust is associated with high densities, meaning that these dusty winds may well carry the bulk of the
mass in these outflows, providing a long-sought link between black hole growth and powerful feedback into
No current physical model is able to explain the dusty wind features. A favoured mechanism for launching such a wind is optical and ultraviolet radiation pressure from the accretion disk onto the dusty gas, as well as infrared radiation pressure from the dusty gas itself. These processes are not considered in models yet in a self-consistent way since they connect global with local emitting processes, which is very computationally expensive and needs advanced simulation techniques. In the course of the proposed PhD project, you will contribute to a large, ERC-funded effort with the goal of developing a new model for 3-dimensional radiative hydrodynamical simulations of dust and gas around actively growing supermassive black holes. The project will train you in high-performance computing, radiative transfer, hydrodynamics, and statistical interpretation.
Planetary magnetospheres represent wonderful natural plasma physics laboratories. The gas giant planets
Saturn and Jupiter host giant magnetospheres, with volcanic moons loading the magnetospheres with mass,
and rapidly rotating planets with strong magnetic fields influencing the motion of plasma on magnetic
field lines stretching from the northern and southern polar regions (where the aurora form) to the
magnetotail or out into the solar wind.
The Cassini mission was one of the most successful planetary missions ever, and ended in dramatic fashion in September 2017, leaving behind 13 years of a rich dataset to explore and many unanswered questions about Saturn's magnetospheric dynamics. Meanwhile the Galileo spacecraft spent several years orbiting Jupiter, and the Juno spacecraft is currently there, focusing on the polar regions where the dynamic aurora form.
This project will combine magnetic field and plasma data from within these magnetospheres with auroral images to track how plasma and magnetic fields move around in these environments. The ultimate aim of the project is to gain a synergistic picture of how plasma and magnetic fields cycle around these huge and complex magnetospheres, and how these dynamics are observable remotely using auroral emissions. The project will involve a combination of data analysis and theoretical work.
Substorms are regular disturbances to near-Earth space which dissipate a considerable amount of energy
into the upper atmosphere. Substorm onset is the point at which the magnetosphere, loaded with magnetic
flux and energy from the interaction with the solar wind, becomes unstable and the stored energy is released.
Auroral particle precipitation around substorm onset deposits energy to the atmosphere. However, the precise
connection between the magnetosphere and ionosphere remains a critical element in all substorm models that is
not well understood. So far satellite-based point measurements or global magnetic indices have been used to
estimate the precipitation, but these cannot accurately represent the rapid changes in precipitation associated
with substorms. However, we now have access to long time series of Auroral Kilometric Radiation (AKR) - measurements
of Earth's radio emissions which respond to substorms. Southampton's Space Environment Physics Group also operate
auroral cameras in the high Arctic which can directly measure substorm-associated precipitating energy flux.
The aim of this project is to combine space-based AKR measurements with ground-based camera data to parameterize the energy deposition into the ionosphere through substorm-associated particle precipitation. This work will significantly advance our understanding of the impact of Space Weather on the Earth's upper atmosphere.
It has long been known that radio emissions are a key tool for monitoring Space Weather and
magnetospheric changes, with direct connection to Earth's atmosphere. Individual case studies have
highlighted the relevant changes to search for: intensity increases, and shifts in frequency linked
to motion of radio sources to different altitudes in the ionosphere.
This project will involve handling large datasets from spacecraft in orbit around Earth which have been monitoring the radio emissions quasi-continuously since the 1990s. These datasets will be systematically probed for changes in power, polarization and frequency which are all characteristic signatures of this energy cycling process.
The student will build domain knowledge of radio emissions from examination of classic case studies which show the response to substorm onset. This will then be used to build machine learning training libraries. Important challenges include exploring how radio signatures alter as they propagate through the ionosphere, and monitoring by multiple spacecraft in different positions will be critical here (with research results directly relevant to the satellite communications sector). The main focus and deliverable at the end of the project will be sophisticated automated algorithms to select relevant features from large catalogues of radio data.
The origin of UV and optical variability from Active Galactic Nuclei (AGN) is not well understood.
It may be caused by reprocessing of X-ray emission, coming from very near to the central supermassive
black hole (SMBH), by the surrounding accretion disc and broad line region (BLR) gas. Alternatively
it might be caused by accretion rate fluctuations in the disc. These possibilities can be tested by
measuring the time lags between the X-ray emission and the emission in the UV and optical bands.
Different physical scenarios result in different time lag patterns. In the reprocessing scenario,
the lags map out the temperature structure of the accretion disc and the geometry of the surrounding
gas, in a process known as 'reverberation mapping'. These structure are far too small to map by direct
imaging or any other method.
Southampton is one of the major world research groups in the study of AGN variability and we lead many of the largest X-ray/UV/optical monitoring programmes, eg using the Swift multiwaveband observatory and the XMM-Newton X-ray/UV observatory. In particular, a huge observational program with Swift will be complete by early 2018, ideally timed for a new student.
The current project consists of both observation and computer modelling. The successful student will analyse these world-leading datasets to map out the inner structures of AGN and will also build a computer model of the expected emission from the accretion disc and BLR gas. By comparing observation with theory we will determine the inner geometry of AGN, including both the X-ray source geometry and that of the inner part of the accretion disc.
Mass is the most fundamental parameter of a black hole and almost all other studies of black holes rely
on an accurate measurement of mass. However mass is often very difficult to measure, eg in optically obscured AGN.
However accreting black holes of all masses emit rapidly variable X-ray emission. Are there any ''characteristic
timescales'' in the X-ray variations which might be related to either the mass and/or to the accretion rate onto the
We have shown previously that the X-ray power spectral densities (PSDs) of accreting black holes can usually be described by a bending power law and that the timescale of the PSD bend is related to the mass and, possibly, also to the accretion rate (eg McHardy et al 2006, Nature, 325, 696). We have also shown that the normalisation of the high frequency part of the PSD is related to mass (McHardy 2013, MN, 430, 49). These early studies were based on inhomogeneous data from many observers. We now have much better data and also we have developed a very powerful analysis technique which will measure the bend timescales and normalisations much more precisely. The aim of this project is to determine precisely how PSD bend timescales and normalisations, in both AGN and X-ray binary systems, depend on mass, and whether accretion rate is important. We will thus produce the most accurate method of measuring black hole masses across all mass scales.
We think that X-rays are emitted from a very compact region around black holes and, in Active Galaxies, we think that
X-rays drive much of the UV and optical variability. But our understanding is vague, mainly because we don't know the
geometry of either the X-ray source or the surrounding material, eg the accretion disc which feeds fuel into the black hole.
For example, is the X-ray source a sphere, surrounding the black hole, or is it more flattened, spreading out over the
accretion disc? And what is the geometry of the inner part of the accretion disc? Is is flat, or is it highly inflated,
thereby stopping X-rays from directly hitting the outer disc to produce UV and optical emission?
The inner geometry of the X-ray source and disc can, however, be measured via a technique called 'X-ray cross-spectral analysis'. This Fourier-based technique enables us to measure the lag, as a function of Fourier Frequency, between high energy X-rays which have travelled directly to the observer, and X-rays which have first hit surrounding material and been reprocessed to lower energies. The lags between the X-ray bands contain detailed information about the source geometry very close to the black hole (eg Emmanoulopoulos et al 2014, MNRAS, 439, 3931).
To properly understand what the lags are telling us we need to build a computer model of the system to compare model predictions with observed lags. We have begun building a General Relativistic model, using MATHEMATICA, which traces the paths of direct and reprocessed rays. At present the model consists of a single point X-ray source (ie the commonly used 'lamp post' approximation). The aim of the present project will be to make realistic 3D X-ray source geometries by combining together many point sources, and to compare the results with observations from a 'Large Project' which has just been approved for late 2018 to measure lags.
This work will be supervised jointly by Professor Leor Barack in the General Relativity Group of the Mathematics Department and Professor Ian McHardy in the Astronomy Group in the Physics and Astronomy Department of Southampton University.
The best sample of nearby galaxies, ie the most complete and best studied in all wavebands,
is the Palomar Sample (Ho et al 1995, ApJ 98, 477). We are currently leading the deepest, and highest resolution,
radio survey of all 280 northern Palomar galaxies with the eMERLIN radio array at both 1.4 and 5 GHz. We are also
carrying out a major X-ray survey with Chandra. Hubble Space Telescope imaging, and infrared imaging, already exists
for all galaxies.
With linear resolution of ~few parsecs on most galaxies we can detect faint radio emission from low luminosity active galactic nuclei (LLAGN) and distinguish it from supernovae or other stellar sources of radio emission. We have nearly completed the 1.4 GHz survey and find many strange and fascinating radio morphologies, such as tiny jets. The future student will concentrate on the 5 GHz survey, which will have 3x higher resolution and be more sensitive still to LLAGN. At low luminosities, radio is the most sensitive probe of AGN activity.
There are a number of important science aims, including: 1) carrying out a census of accretion in the local universe 2) determining the relationship between radio luminosity, X-ray luminosity and LLAGN black hole mass (the 'Fundamental Plane' of black hole accretion, which places strong constraints on jet models 3) determining the relationship between LLAGN radio power and radio morphology and optical host galaxy morphology.
Exploding stars, or supernovae, impact upon many diverse areas of astrophysics, from galaxy formation, to stellar
evolution, to cosmology and studies of dark energy. The next few years will see a revolution in this field,
with the numbers of objects available to study rising from the hundreds to thousands and tens of thousands per year.
In particular, two major new facilities will revolutionise the study of supernovae: the first is the billion-dollar
Large Synoptic Survey Telescope (LSST), an 8-m survey telescope that will image the whole sky every 3 days, and which
will find new supernova explosions at an unprecedented rate. The second is the 4MOST multi-object spectrograph, which will
study thousands of supernova explosions in great detail as part of its TIme Domain Extragalactic Survey (TIDES). This
combination will provide the ultimate cosmological sample of type Ia supernovae, probing completely new parts of time-domain
parameter space, and Southampton is involved in this key work.
This project will use scientific results based on existing samples of supernovae - from the Dark Energy Survey, the OzDES survey, and the Palomar Transient Factory - to prepare for the advent of these new facilities. This will involve developing new techniques to classify large samples of supernova events based only on photometric data (with immediate application to existing Dark Energy Survey data), and the calculation of the rate of occurrence of exotic supernova explosions. This is the perfect opportunity to get involved in two major new surveys from the start of their operations.
Lenticular (S0) galaxies are a special class of bulged galaxies in between ellipticals and spirals. They
are often characterized by lower specific star formation rates and no clear spiral patterns, with a broad
variety of structural properties, going from galaxies with very big bulges to others dominated by the disc component.
After almost one century since their definition, the origin of lenticular galaxies is still a matter of debate.
This project aims at probing the formation and evolution of bulged galaxies, with a specific focus on lenticulars/S0s,
using a cutting-edge methodology based on extensive, advanced semi-empirical models which make use of sub-halo abundance
matching and halo occupation distribution techniques.
The main objectives of this proposal are the following:
- Analyse in a cosmological context through advanced semi-empirical models, an array of key physical processes to form and evolve lenticulars, such as mergers, bar/disc instabilities, disc regrowth, clumpy accretion, morphological and/or halo and/or environmental quenching. Several of the latter physical processes are still nearly unexplored in this context.
- Compare the outputs of each different model with the statistical, spectral, morphological, structural, and environmental properties of lenticulars.
We will make extensive use of new, unique, and comprehensive data sets available to our group from, e.g., SDSS and COSMOS, specifically catalogued for S0 galaxies in different environments and redshifts.
The University of Southampton has just launched the Centre for Doctoral Training in Next Generation Computational Modelling. The NGCM, which is funded by EPSRC, brings together world-class computational simulation and modelling research activities from across the University of Southampton and hosts a 4-year doctoral training programme that is the first of its kind in the UK. If accepted onto this program students will spend the first year studying simulation and modelling techniques and, at Easter of year 1, will select a specific research program for the next 3 years. This research program could be in a variety of disciplines, including Astronomy. Potential research programs are not yet finalised but, in the first instance, interested students should visit the NGCM web site (http://ngcm.soton.ac.uk/index.html).Last updated 2nd December 2016 PhDAdmissionCoordinator