Supervisor: Dr Clément Bonnerot

When a star wanders too close to a supermassive black hole, it gets torn apart by extreme gravitational forces, leading to a powerful flash of light detectable billions of light years away. These phenomena, referred to as “tidal disruption events”, represent unique probes of supermassive black holes that lie otherwise undetectable in the centres of galaxies. While a few tens of such events have been observed so far, thousands of new detections will be made by the Rubin Observatory starting next year.

The main goal of this PhD project is to develop the theoretical understanding needed to optimally interpret the emission received from tidal disruption events at the dawn of this observational golden era. This work will involve pen-and-paper theory, writing code to solve equations, and running numerical simulations on supercomputers, in order to predict the evolution around the black hole of the gas stripped from the disrupted star and the resulting emission to be detected by telescopes. Depending on specific interest, the project can involve various branches of astrophysics, such as gas dynamics, magnetic fields, electromagnetic radiation, and general relativity.

If you require any additional information, do not hesitate to contact Clément Bonnerot by email (c.a.bonnerot@bham.ac.uk).

Supervisor: Dr Suhail Dhawan

The measurement of the expansion rate of the universe, i.e. the Hubble Constant has been of interest to astronomers for nearly a century. The current most precise local distance ladder estimate of the Hubble Constant from Cepheid variables calibrating the Type Ia supernova luminosity is in very significant tension with the global inference from the early universe - predicted from the well tested standard cosmological model. This could either be a sign of new cosmological physics or unknown systematics in the measurement. A powerful route to answer the question is measuring the Hubble Constant independent of the distance ladder. Strong gravitationally lensed supernovae offer a new channel to measure H0.  The delay in arrival time between multiple images of the lensed object is sensitive to the gravitational potential of the deflector galaxy and H0. The PhD project will involve developing lensed supernovae as precision probes of cosmology via one or more of the following tasks: 

• Developing spectroscopic time-delay measurements using distinct features of supernovae in the evolution of the spectral energy distribution
• Constructing a set of selection criteria for implementing follow-up strategies to discover lensed supernovae promptly
• Building inference tools for time-delays and ultimately H0 using hierarchical Bayesian methods

To achieve the above aims the student will use the live data stream from transient surveys like Vera C. Rubin Observatory’s LSST, the Dark Energy Survey, ZTF as well as exclusive access to facilities like the SOAR telescope, the VLT, 4MOST and JWST for detailed studies of lensed SNe. Please feel free to reach out for more information and associated publication lists.

If you require any additional information, do not hesitate to contact Suhail Dhawan by email (sdhawan@star.sr.bham.ac.uk).

Supervisor: Dr Ben Gompertz

Gamma-ray bursts are the most powerful explosive events in the universe, releasing as much energy in 10 seconds as the entire Milky Way galaxy does in several years. They are associated with either the collapse of very massive stars (long gamma-ray bursts) or collisions between two neutron stars or a neutron star and a black hole (short gamma-ray bursts). Because of this, gamma-ray bursts can tell us about some of the most extreme environments in nature, and are confirmed counterparts to gravitational-wave sources.

This project focuses on the engines powering 'ultra-long' gamma-ray bursts. Unlike normal events lasting seconds to minutes, these colossal explosions have durations measured in hours or even days, requiring novel engines to drive them. They are sometimes seen with unusually bright supernovae whose evolution suggests they could be powered by an extremely magnetised neutron star that has somehow resisted collapsing to a black hole. Students will have the opportunity to research the systems that produce gamma-ray bursts; the environments they explode into; their connection to superluminous supernovae; and how we can use them to probe the interiors of neutron stars, some of the densest objects in the universe.

An interested student will be able to join international collaborations like GOTO, LSST, STARGATE, and ENGRAVE, and gain access to some of the most powerful telescopes and satellite observatories in the world.

For more information, please email Dr. Ben Gompertz (bgompertz[at]star.sr.bham.ac.uk)

Supervisor: Dr Sean McGee

During this PhD, the next generation of telescopes and surveys used to study galaxy formation will become available. This includes new observatories like Large Synoptic Survey Telescope, the Euclid space telescope, and the James Webb Space Telescope as well as new instruments like WEAVE on the William Herschel Telescope and MOONS on the Very Large Telescopes. This PhD will prepare and make use of these new tools to examine galaxy formation. 

There are several possible projects including, but not limited to: the tidal disruption of stars by the black holes in galaxies and their subsequent effect on the galaxy hosts; the effect of environment on the formation of galaxies through cosmic time; and constraining the mass function of dark matter halos with strong gravitational lensing.

For more information, please email Dr. Sean McGee (smcgee[at]star.sr.bham.ac.uk)

Supervisor: Prof. Graham Smith

Multi-messenger gravitational lensing is an exciting and rapidly growing field, fuelled by the first discovery of a multiply-imaged supernova, the first direct detection of gravitational waves, and the upcoming Vera C. Rubin Observatory (Rubin) The basic idea is that the flux from some high energy events (e.g. supernovae, gamma ray bursts, and mergers of compact objects) in the distant universe can be magnified and even split in to several images of the same event, by a gravitational lens (galaxy, group or cluster of galaxies) along our line of sight.

Detection and detailed study of this phenomenon probe a wide range of fundamental physics including tests of general relativity, the nature of dark matter, the expansion history of the universe, and the physics of explosive transients and their progenitors in the distant universe. In Birmingham we are at the forefront of multi-messenger gravitational lensing research, including the search for lensed optical counterparts to lensed lensed gravitational wave sources. We are pursuing this research within the framework provided by Rubin's Strong Lensing Science Collaboration, and the LSST:UK Consortium.

A PhD in Birmingham would see students joining these organisations and thus having Rubin data rights, and collaborating with us and our international colleagues on this cutting edge research. The PhD project will be constructed to suit students' strengths and interests, and for example can focus on analysis of observational data aiming to make ground-breaking discoveries, and/or modelling and interpretation of discoveries to learn new physics. To get a flavour of our work and the opportunities available to a new student, please see the links below.

Rubin ToO 2024: Envisioning the Vera C. Rubin Observatory LSST Target of Opportunity program

Discovering gravitationally lensed gravitational waves: predicted rates, candidate selection, and localization with the Vera Rubin Observatory

On the gravitational lensing interpretation of three gravitational wave detections in the mass gap by LIGO and Virgo

Enabling discovery of gravitationally lensed explosive transients: a new method to build an all-sky watch-list of groups and clusters of galaxies

Strong Lensing Science Collaboration input to the on-sky commissioning of the Vera Rubin Observatory

What does strong gravitational lensing? The mass and redshift distribution of high-magnification lenses

On building a cluster watchlist for identifying strongly lensed supernovae, gravitational waves and kilonovae

Deep and rapid observations of strong-lensing galaxy clusters within the sky localization of GW170814

What if LIGO's gravitational wave detections are strongly lensed by massive galaxy clusters?

For more information, please email Prof. Graham Smith (gps[at]star.sr.bham.ac.uk)