Only 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.

In 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.

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 JWST and WISE (and soon WFIRST) telescopes and Europe's Very Large Telescope 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 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.

When 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 simulations.

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.

The 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 Survey (TIDES).


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.