Dr Andrew Mummery from Oxford’s Department of Physics has been recognised by the International Astronomical Union and the Royal Astronomical Society for his thesis. He has been awarded the IAU’s Division D High Energy Phenomena and Fundamental Physics PhD Prize and is runner-up of the Royal Astronomical Society’s Michael Penston Thesis Prize.
In his thesis entitled 'Illuminating tidal disruption events with a time-dependent theory of relativistic accretion discs', he studies one the most extreme astrophysical events in our universe: tidal disruption events. These occur in the centre of galaxies, where supermassive black holes (black holes with masses of more than a million times that of our sun) are situated and stellar densities are high. If an unfortunate star ventures too close to this black hole, it can be tidally destroyed, in its entirety, by the black hole’s gravitational forces. The debris from this event then rains back towards the black hole, causing bright flares from otherwise quiescent galactic centres. To probe the properties of the black holes in the centre of tidal disruption events, one must understand in detail the physics of the discs of stellar debris which form in their aftermath. In his thesis, Dr Mummery developed a new time-dependent and relativistic theory of accretion discs, which he then utilised to analyse the observed luminosity of tidal disruption events. This model takes as input data taken simultaneously across a wide range of observing frequencies (from infra-red all the way up to X-ray), and returns the properties (the mass and rate of rotation) of the black holes at the centre of these events.
‘I thoroughly enjoyed my 4 years in the astrophysics sub-department and I am delighted to have my work recognised by these two institutions,’ comments Dr Mummery. ‘As a Leverhulme-Peierls Fellow at Oxford’s Department of Physics, I am extending the ideas developed in my thesis, in anticipation for forthcoming large data sets of these objects discovered by the new observational survey LSST.'
Dr Mummery studied for his DPhil under the supervision of Professor Steven Balbus: 'Andy took some ideas and results which were barely passed their teething stage, and turned them into a full-fledged cottage industry. In his hands, tidal disruption events have gone from astrophysical curiosities to diagnostic tools of remarkable power for studying black hole populations. His thesis blends fundamental relativistic fluid theory with detailed observations in a very beautiful way.'
Read more on the RAS website: https://ras.ac.uk/news-and-press/news/2022-thesis-prize-winners-announced
Read more on the IAU website: https://www.iau.org/news/announcements/detail/ann23019/