Gamma Ray Bursts

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Gamma-ray bursts (GRBs) are the most powerful explosive events in the Universe (after the Big Bang). Two classes are recognised: the longer bursts occur when a massive star collapses at the end of its life, while bursts shorter than around 2 seconds are thought to be due to the collision of two neutrons stars (or a NS and a black hole) as their mutual orbit decays due to gravitational radiation. In both cases a black hole is born which accretes matter for a brief time and launches two, narrow, highly relativistic jets. The bright prompt emission is usually over very quickly - the "burst'' - but further emission occurs as the jets give up their energy via interaction with the surrounding circum-stellar and inter-stellar material. This "afterglow'' emission fades gradually over periods ranging from hours to weeks and can be detected across the electromagnetic spectrum.

At Leicester we study the origin and evolution of GRBs using multi-waveband data obtained from a wide variety of satellite and ground-based observatories. In addition, we have a theoretical programme aimed at modelling the origin and evolution of GRBs. Current research at Leicester is aimed at understanding both the prompt emission from the burst and the longer-lived afterglow. This emission allows us to probe the innermost regions of the rapidly expanding fireball around the GRB and the nature of the relativistic jets launched along the black-hole rotation axis during the explosion. We also probe the link between supernovae and GRBs.

Much of our work uses data from the Swift satellite for which we provided the X-ray camera. Detailed information on Swift can be found on the web pages for the UK Swift Data Centre which is based at Leicester. This includes an introduction to gamma-ray bursts.

A summary of some of our recent research on GRBs can be found here.

Information on our hardware role in the Swift GRB satellite mission can be found here.

Contact: Paul O'Brien (pto@star.le.ac.uk)

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