Cancelado (plano de contingência UC / covid-19): Gamma-Ray Burst Polarimetry with POLAR and POLAR-2

by Merlin Kole (University of Geneva)

Friday 13 Mar 2020, 14:00 → 15:00 Portugal

Sala de Conferências (Departamento de Física)

Gamma-Ray Bursts are the brightest electro-magnetic explosions in the Universe since the Big Bang. Despite over 50 years of research on these extreme phenomena, during which the majority of the properties of most messengers from these events have been measured, many open questions about their nature and the environments in which the emission takes place remain. Polarization measurements of the high-energy emission have long been theorized to be able to answer most of these questions. Polarization measurements are, however, extremely complex to perform due to the low sensitivity of the instruments employed as well as the large systematic errors resulting from instrumental effects. The POLAR detector was a dedicated Gamma-Ray Burst polarimeter developed by a Swiss, Chinese and Polish collaboration. The instrument was launched together with the second Chinese Space Lab, the Tiangong-2, in September 2016 after which it took 6 months of scientific data. During this period POLAR detector a total of 55 GRBs of which 14 are bright enough to allow for statistically constraining polarization measurements. I will present the POLAR mission, the methodology used to perform the polarization analysis and the measurements results. These results have, however, not been able to answer many questions but have instead raised new ones. In order to answer these the POLAR-2 mission was initiated. The POLAR-2 detector will have a sensitivity 10 times larger than POLAR and will be launched in early 2024. I will describe both the instrument design and the scientific prospects of this mission.