Transient Engine Driven Explosions

Project Information

TEDE

Grant agreement ID: 725246

DOI

10.3030/725246

Project closed

EC signature date 22 February 2017

Start date 1 April 2017

End date 31 March 2023

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 987 299,25

EU contribution

€ 1 987 299,25

Coordinated by

STICHTING RADBOUD UNIVERSITEIT
Netherlands

Periodic Reporting for period 5 - TEDE (Transient Engine Driven Explosions)

Reporting period: 2022-04-01 to 2023-03-31

Summary of the context and overall objectives of the project

Stars end their lives in many ways. Some fade away, others explode. More rarely they may collide with another star, or be torn apart by the strong gravity from a black hole. It is an irony of stellar evolution that many stars are actually at their brightest at the moment of their death, creating signatures which can be seen at great distances – much further than the star could be seen during its life. This means that stellar death provides a unique window both into the nature of the stars and their evolution, but also into the extreme physics which acts upon them at the moment of their demise. The extreme brightness of these stellar deaths also means they can be used as lighthouses to probe the distant Universe.

This ERC project focussed on understanding the nature of stellar deaths which are powered by a compact object (usually a neutron star or a black hole) that 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.

Core results from the grant include:

1) The discovery of the first electromagnetic counterparts to gravitational wave sources
2) The identification of kilonova in long-duration gamma-ray bursts, demonstrating a hitherto unexpected origin
3) The first James Webb Space Telescope observations of long duration gamma-ray bursts
4) The discovery of new forms of tidal disruption event, both relativistic and thermal
5) The discovery of the first gamma-ray burst formed by dynamical processes (collisions) in the dense nuclei of galaxies
6) Studies of the brightest gamma-ray burst of all time.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Progress has been made across the areas of interest for the project. A particular highlight is the discovery of one source -- a pair of merging neutron stars – in both gravitational waves and light (a central goal of goals 3 & 4 above). My team was centrally involved in this work, both in the initial discovery of the source with light and with in-depth follow-up, leading observations from the Very Large Telescope and the Hubble Space Telescope. Team members presented these results at press conferences in Munich and Washington DC. Further work has demonstrated the link between these sources and short-duration gamma-ray bursts, linked them with the synthesis of very heavy elements and provided a new route to measuring the expansion rate of the Universe. More recently, and surprisingly, our work has shown that some of the long GRBs are also actually created through the merger of two neutron stars in an unexpected

We have also made progress in understanding the nature of tidal disruption events which produce material moving close to the speed of light. 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.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The project is now complete. No new results are expected from it.

GW170817 as seen by our Hubble Space Telescope observations (credit, Levan, Tanvir, NASA/ESA)