Research Projects

Gamma-ray bursts during the Swift Era: back to the blackboard

The purpose of this placement is to review the science of Gamma-Ray Bursts from the perspective of the observers. Since the launch of SWIFT, in 2004, a lot of new observations have been provided to explain the phenomenon, but interestingly several common features that were observed in pre-SWIFT events have now totally disappeared. The successful student will review the observations of pre-SWIFT and SWIFT events to list all common features that were known, and will try to explain why some are not more observed. If possible, he/she will also try to discuss the validity of the various models currently offered in light of the observational results.

Gamma-Ray Bursts (GRBs) are powerful explosions occurring at the distant edge of the Universe. They have been discovered in the mid-seventies as bursts of gamma-ray photons by military satellites, and since then have puzzled the scientific community by their extreme properties. It is understood that the physics at play within a GRB implies ultra-relativistic speeds, huge magnetic fields, and extremely hot plasma.

The history of GRBs can be phased in 4 main eras: the pioneer one, using very simple instruments; the BATSE era with a dedicated satellite to study their spectra; the BeppoSAX era to locate them; and the Swift era to produce a large bulk of data. We are now in a time where some data are not even considered because there are too many of them to analyse.

Interestingly, before the launch of SWIFT, a lot of features were commonly observed within the datasets, such as precursors, XRFs, early optical flashes. SWIFT, albeit having shown that the early phase of the phenomenon was far more complex than thought, has no more detected these features; several empirical relations were not more observed; and a huge new load of models have been pushed to explain the current observations with no respect for the previous ones. It is thus time to go back to the blackboard, and to understand the observations available.

In fact, each instrument has its bias, and so far none of the SWIFT ones have been really considered. This project will push you to study the GRBs from the observational point of view, i.e. without any a-priory on any model offered to explain the observations. You will try to remove all possible biases from all the previous observations in order to recover the global, unbiased, picture, and then will try to see which models could explain them and which ones cannot.

Relevant documents: The Physics of Gamma-Ray Bursts by Bing Zhang. ISBN: 978-1-139-22653-0. Cambridge Univeristy Press, 2018. Prerequisite: working knowledge of Matlab and/or Python; fair understanding of the high energy physics; previous experience with Linux and the command line.

This work may continue for a PhD thesis.