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 Diego Altamirano 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 starting on January 31st 2023, 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 Diego Altamirano
Room 4076 (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 (you have to search for PhD Physics, with Programme:Research and in the 2023-2024 academic year -- you can alternatively apply for PhD Physcis & Astronomy Mayflower - you do not need to submit multiple applications). If requested, please specify "Astrophysics" in the "Topic of field or research" section to have your application directed to the astronomy group.
For part-time research, please use the same link above but also contact Dr. Diego Altamirano for more information.
To download the application guide, please click here.
For more information on how to apply and online application form please visit the University web page.
a small fraction of supermassive black holes is currently
actively accreting gas and emitting
energy into their surroundings. The active states are called Active Galactic Nuclei (AGN) but most
supermassive black holes are inactive or accreting gas at an extremely low rate. We still do not
know what physical processes control if black holes are active or inactive.
this project the student will investigate a new class of AGN
that may shed light on the process of
black hole activation. These are called Changing-Look AGN and are observed to transition
between active and inactive states in a matter of years or decades. The student will use multi-
wavelength observations to study the properties of Changing-Look AGN and determine how they
differ from other AGN. The student will also have the chance to propose new observations of
recently discovered Changing-Look AGN using ground-based and space-based telescopes.
holes are the densest form of collapsed matter. Understanding
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 JWST and WISE (and soon WFIRST) telescopes and Europe's Very Large Telescope interferometer will be available in the infrared.
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 abroad observing, collaborations, data analysis. You will
learn big data analysis from very large surveys, and develop expertise in statistical
techniques with wide applicability beyond astrophysics.
the solar wind interacts with Earth’s magnetosphere, it is
heated and slowed from supersonic to subsonic speeds at the
bow shock. Shockwaves in space are ‘collisioness’ – the energy
in the flow cannot be dissipated by particle collisions
(viscosity) since the density is far too low. Instead,
electromagnetic effects at the smallest plasma scales must be
responsible. These processes lead to a turbulent and strongly
time-dependent shock transition region. Observations of
Earth’s bow shock and the magnetosheath by state-of-the-art
missions such as Magnetospheric Multiscale (MMS) enable
high-resolution exploration of the 3D micro-physics of these
regions at a particular snapshot in time. Furthermore, ‘string
of pearls’ configurations of all 4 MMS spacecraft allow us
capture shock processes at different times, effectively
allowing us to directly observe how they evolve. The objective
of this project is therefore to identify and characterise
plasma process in the shock, and then examine how they evolve
in time using a combination of spacecraft observations and
The student will: i) develop methods for identification and classification of time-dependent shock structures such as surface ripples, cyclic shock reformation, stream instabilities, and magnetic reconnection; ii) utilize ‘string of pearls’ and other novel configurations of the MMS spacecraft to track the time evolution of these structures, and iii) directly compare the observed time evolution to that seen in high performance plasma simulations run by the student in Southampton. We may also adapt these methods for use with interplanetary shocks observed by Parker Solar Probe and Solar Orbiter, where serendipitous spacecraft conjunctions allow for observations of time dependence. We also expect these outcomes to aid in preparation for future science with missions such as NASA’s Helioswarm, and the proposed MAKOS mission.
The Earth's magnetic field forms a cavity in the solar wind called the magnetosphere; the interaction between the solar wind and the magnetosphere is ultimately responsible for the dynamics of near-Earth space, including variations in the intensity of the radiation belts and the most spectacular displays of the aurora (the northern and southern lights). The nature of these interactions depends on the orientation of the magnetic field associated with the solar wind (the interplanetary magnetic field, or IMF); a “southward” orientation of the IMF (opposite to the Earth’s magnetic field) 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. Study of the large-scale structure and dynamics of the magnetosphere is highly timely, given the upcoming joint European/Chinese mission SMILE (Solar wind Magnetosphere Ionospheric Link Explorer, expected to launch in 2025). This project will use a combination of space-based observations (e.g. in situ plasma observations from the Cluster, THEMIS and ARTEMIS missions) and ground-based observations (from ionospheric radars such as the SuperDARN consortium and the European Incoherent Scatter radar, EISCAT) to investigate the large-scale structure of the magnetosphere. Possible topics include: the spatial extent of the magnetospheric “cusps”, and how that may depend on solar wind conditions; magnetospheric structure associated with northward IMF conditions; and/or the nature of time-varying magnetic reconnection, which couples the solar wind to the magnetosphere.
accretion of gas onto supermassive black holes is one of the
most efficient known processes
to convert mass to energy. While the black hole is growing in mass, a significant amount of energy
is emitted into its surroundings. These objects are called active supermassive black holes or Active
Galactic Nuclei (AGN) and are observed in the centres of galaxies. Even though only a small
fraction of supermassive black holes is active, AGN are thought to be able to influence the growth
of the galaxies in which they live. In this project the student will use new observations from the European Southern Observatory
(ESO) to 1) investigate how black hole activity varies with time and 2) measure the mass of a large
sample of active supermassive black holes for the first time. Both the variability and mass of the
black holes are key parameters to understanding the physics of black hole accretion and growth.
The student will use their findings to characterise the timescale in which AGN of different
brightness vary and determine how the black hole masses are related to the large-scale properties
of the host galaxies. The student will be part of ESO's 4MOST consortium and TiDES-RM (Time
Domain Extragalactic Survey – Reverberation Mapping), a new survey which will soon start
observing hundreds of AGN.
Supermassive black holes, extreme singularities of spacetime,
of the order of a million to a billion solar masses, are
lurking today in the cores of most galaxies, including our own
Milky Way. The masses of supermassive black holes seem to
correlate with their host galaxy and dark matter halo
properties, in particular to the characteristic random motions
(velocity dispersion) of stars. Observations of the deep
Universe are showing that supermassive black holes as massive
as a billion times the mass of the sun are already present at
early epochs, providing extremely stringent constraints to the
viable formation channels of these monsters.
This project aims at contributing to the still largely unsolved questions in astrophysics: How do supermassive black holes form and evolve? What are the formation channels for their seeds? How much do black-black hole mergers and gas accretion contribute to their mass growth throughout the history of the Universe?
Via the use of advanced semi-empirical models, which make use of sub-halo abundance matching, coupled to the outputs of high-resolution N-body simulations, this project aims at determining the relative roles of quasar feedback and galaxy mergers in setting the scaling relations with velocity dispersion. In turn, the project aims at constraining the radiative efficiency (and thus the spin) of black holes. The project will also make extensive use of a large hydrodynamic simulation run in Southampton, on IRIDIS5, which for the first time includes the dynamical evolution of stellar mass black holes in protogalaxies as a promising route to form the seeds of supermassive black holes in the early Universe.
This project will also set very stringent constraints on the gravitational wave background from supermassive black hole binaries, of capital importance for the next gravitational wave detectors (LISA). The student will contribute to the next-generation European space galaxy missions, Euclid, LSST, SKA and Athena. (Cartoon image of two merging supermassive black holes from Astronomynow.com).
Supernovae are cosmic explosions that have a dramatic
influence across astrophysics: from galaxy formation, to
stellar evolution, to cosmology. The thermonuclear ‘type Ia’
supernovae provide astronomer’s with their best extragalactic
‘standard candle’, and are precise tools to study dark energy
and the expansion rate of the universe. The next five years
will see a revolution in this field: the number of supernovae
discovered will rise from the hundreds, to thousands, to tens
of thousands per year. Southampton has a leading role in two
major new facilities that will drive this: the Vera C, Rubin Observatory conducting
the Legacy Survey of Space and Time (LSST), and the 4MOST multi-object
spectrograph, which will study thousands of supernovae
spectroscopically as part of its TIme Domain Extragalactic
The student will join the Rubin Observatory’s Dark Energy Science Collaboration and use access to proprietary Rubin simulations and astrophysical knowledge of supernovae, to prepare for the science exploitation of the first data from these new facilities. This will involve developing new techniques to analyse large samples of supernova events. The project will then analyse the first data, focusing on the first few thousand type Ia supernovae. They will generate separate cosmological analyses (‘Hubble diagrams’) as a function of astrophysical variables, investigating the dependence of supernova distances on host galaxy stellar mass, star-formation rate and dust, as well as the supernova colour and other astrophysical systematics. The result will be an improved understanding of type Ia supernovae that will underpin the next generation of cosmological measurements.
Neutron stars (NSs) are compact objects. The tiny NSs being no
more than 20-30 km in diameter but containing masses of 1 to 3
times the Sun, represent extremes of gravity, pressure and
density, making them the only stars where matter burns on the
outside. Fortunately, some NS have close companion stars; gas
from these stars, attracted by the compact object strong
gravity, funnels and spirals towards it, forming an accretion
disk. These systems are called NS low-mass X-ray binaries
(LMXBs); the most powerful phenomena we observe from them are
directly related to these accretion disks, as a large amount
of gravitational energy is released when the matter approaches
the compact object. This causes the inner accretion disk to
reach temperatures as high as 100 million degrees and
therefore to emit the bulk of the energy in the X-ray band of
the spectrum. It is the flow of this accreting plasma onto the
NS which provides one of the very few opportunities to
directly probe the properties of the tiny (few km) regions
where we can "see" General Relativity effects in action in
otherwise inaccessible regimes.
This project will make use of high-time and high-energy resolution X-ray data from the Neutron star Interior Composition Explorer (NICER) to understand the physics of millisecond X-ray variations seen only around NS. NICER is the state-of-the-art NASA mission dedicated to the study of the extraordinary gravitational, electromagnetic, and nuclear physics environments embodied by neutron stars. The student will join the high-energy astrophysics group at Southampton, and will have the opportunity to collaborate with researchers from around the world.
Galaxies in the local Universe appear with a variety of
morphologies from discs to massive spheroids (ellipticals).
The origin of bulged galaxies is still a matter of debate, but
even more intriguing is the question “why do some galaxies
stop forming stars”?. This project aims at probing the
formation and evolution of bulged galaxies and then to move on
dissecting the origin of the halting of star formation in
galaxies. A variety of models have been put forward in the
literature to explain the origin of galaxies “quenching”, from
the mass of the host dark matter halo, the mass of the central
bulge, the structure of the galaxy, and last but not least the
effect of the feedback from a central supermassive black hole.
In this project, we will explore in a comprehensive fashion all possible routes to quench galaxies by making use of cutting-edge data-driven models which make use of sub-halo abundance matching and halo occupation distribution techniques and as such are characterised by a lower number of free parameters then more traditional approaches.
The main objectives of this project are to:
- Analyse, in a cosmological context, an array of key physical processes to form and evolve bulged galaxies, 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 bulged galaxies.
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 bulged galaxies in different environments and redshifts.