Research Projects

The nature and properties of ultra-long gamma-ray bursts

The purpose of this placement is to study the class of the ultra-long Gamma-Ray Bursts and its properties, and to link them with the potential population III stars and the surrounding medium properties of the early universe. The study will start with a complete review of the current paradigm of ulGRBs, and some training on the data analysis needed for performing the placement. The successful student will then gather all available data about previous ulGRB events in order to extract as much information as possible from the current datasets available. Pending a new detection, the student may also work on new data (observations requested on several observatories) and will help in the request of observation time on spatial observatories.

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.

Ultra-long GRBs are the most extreme of the extreme events. They are extremely rare (fewer than 20 events are known despite more than 40 years of observations of GRBs!), and are assumed to be the swan song of the most massive stars of the universes. Their discovery is recent, compared to normal long GRBs, as it is in 2011 that the first of these events was recognised as ultra-long. So far, there is still a passionate debate about the exact mechanism able to produce such an event, which is not settled. The purpose of the placement is to gather all possible observations taken so far and to analyse them using the same method for removing any bias. The successful student will then extract from the observations as much information as possible and confront these with the key models offered to explain the ulGRBs.

As this is a hot topic, it is possible that during the placement a new event would be detected. Dr. Gendre is in contact with various European teams and has access to dedicated observation time in such a case: should a new ulGRB be detected, the student will have to assist the team in the analysis of the new data.

Relevant documents: The Physics of Gamma-Ray Bursts by Bing Zhang. ISBN: 978-1-139-22653-0. Cambridge Univeristy Press, 2018.

Prerequisite: a working knowledge of Matlab or Python; some experience with Linux and the command line; a fair understanding of small number statistics (Poisson); a good level of computer science in order to create scripts and pipelines of reductions.

This work may continue for a PhD thesis.