Periodic Reporting for period 3 - TEDE (Transient Engine Driven Explosions)
Reporting period: 2019-03-01 to 2020-08-31
This ERC project is focussed on understanding the nature of stellar deaths which are powered by a compact object (usually a neutron star or a black hole) which resides at the centre of the explosion. The energy released from this central engine can transform the explosion, making it brighter than it may otherwise be or allowing other extreme physical processes, such as the synthesis of heavy elements, to occur. The aim of this project is to understand how these central engines impact explosions, from their observational appearance, to a test of the ubiquity of black holes in galaxies, to a route to testing the origin of the heaviest elements.
There were for key areas for work identified.
1) The origin of the longest duration gamma-ray bursts. How are they created? What is their relation to ""normal"" gamma-ray bursts?
2) The nature of tidal disruption events where stars are shredded by massive black holes. Measuring the diversity of their observational properties and the ubiquity of black holes in the nuclei of galaxies.
3) The nature of short-duration gamma-ray bursts. Are they caused by the merger of compact objects such as neutron stars and black holes?
4) The first optical counterparts of binary mergers seen with gravitational waves."
We have also made progress in understanding the nature of tidal disruption events which produce material moving close to the speed of light (item 1). We have published the first time-resolved polarisation of the jet associated with one of these events, as well as Hubble Space Telescope imaging of another example demonstrating it to arise from a merging galaxy, consistent with the idea that such mergers increase the rate of tidal disruptions. More recently we have also undertaken studies of very long-lived GRBs, and used these as a probe of extreme physics, with some very high energy photons being detected from ground-based telescopes minutes to hours after the event. We have also capitalised on recent theoretical work which suggests long-lived gamma-ray bursts may be responsible for some heavy element production and have launched a major campaign at a local long-duration GRB from August.