Gamma ray burst astrophysics

For around 30 years after their discovery in the late 1960s, gamma-ray bursts were one of astronomy's biggest mysteries. The locations of gamma ray bursts were finally localised with enough precision to search for X-ray and optical afterglows, and identify the galaxies in which they originate, in the late 1990s. In 2004, NASA's Swift observatory was launched, which localises gamma ray bursts autonomously as they are happening, and slews within 90 seconds to bring its Optical/UV Telescope and X-ray Telescope to capture the afterglow within a few minutes of the burst. We now know that long gamma-ray bursts (with durations longer than 2 seconds) occur in the hypernova explosions that end the lives of massive stars, and that the short gamma-ray bursts are likely to come from the merging of neutron star binaries. The physics of the explosion and subsequent afterglow are hot topics of debate. Swift, together with ground based telescopes and other space observatories, are providing a wealth of data on gamma ray bursts and their afterglows. The Optical/Ultraviolet Telescope (UVOT) onboard Swift was designed and constructed at MSSL, and we host an operations team which plays a major role in the Swift observatory, analysing the gamma-ray burst data as it comes down from Swift.

This project is for a PhD student to work alongside our operations team in studying gamma-ray bursts and to utilise the large body of UVOT data to further our understanding of the physics of these phenomenal explosions: how they are powered, how the relativistic blastwave deposits its energy into the surrounding medium, the environments in which gamma-ray bursts occur, what the progenitor stars could be, and what gamma-ray bursts tell us about the cosmic history of star and galaxy formation. The student will examine correlations between the gamma-ray and optical energetics, building on the correlation we recently found between the brightness of the afterglow and the speed with which it fades (Oates, Page et al. 2012, MNRAS 426, L26). The student will also experience real-time investigation and follow up of gamma-ray bursts, starting within the first few minutes of a burst being detected with Swift, with the opportunity to study in detail any exceptional bursts that go off when the student is on duty.

The student will develop a front-line understanding of the physics of these explosions, and contribute to improving this understanding.