Studying the Universe though gamma-ray polarization

by Dr Merlin Kole (UNIGE · Department of Particle Physics)

Wednesday 25 Jan 2023, 14:00 → 15:00 Portugal

Sala de Conferências (Departamento de Física FCTUC)

After more than 5 decades since their discovery Gamma-Ray Bursts (GRBs) remain one of the most studied astrophysical sources in the Universe. Seen approximately once per day, these cosmic explosions lasting several seconds consist of an initial bright burst of gamma-ray emission which typically outshines all other objects in the sky. The gamma-ray emission is followed by an afterglow which can last from days up to months and has been observed over the full electromagnetic spectrum.

Despite the observation of 1000's of GRBs over the years much remains unknown about these phenomena. While the detection of gravitational waves coincident with a GRB in 2017 taught us that short GRBs are likely the result of the merger of binary neutron star systems, longer GRBs are thought to originate from the death of massive stars. As such, GRBs involve physics at the extreme, with complex gravitational fields, extreme temperatures and energies and strong magnetic fields. Therefore, the details on how, for example, the large amount of gamma-ray emission is produced remains poorly understood. Polarization measurements of these gamma-rays, although being notoriously difficult to perform, are thought to be able to provide valuable insight into GRBs.

During this talk I will provide an overview of how polarization measurements can provide us with insights into some of the most complex phenomena in astrophysics and present the first detailed polarization measurements performed by the POLAR mission. In addition, I will discuss the future of gamma-ray polarimetry by focusing on two upcoming missions, POLAR-2 and LEAP, and how such instruments can change our understanding of GRBs in the coming years.