2024.02.08 - Ramandeep Gill
Channel: Coloquio IRyA
Date: 09/02/2024

Speaker info: Dr. Ramandeep Gill, IRyA-UNAM
https://www.irya.unam.mx/web/en/people/research-staff/r-gill
https://ramandeepgill.com/

Title: GRB jet structure and magnetic field revealed by new observations
Abstract:
The angular structure of ultrarelativistic jets in gamma-ray bursts (GRBs) is shaped by their interaction with the medium that initially confines them, namely the internal media of their progenitor stars in long-duration GRBs. For the majority of GRBs observed thus far, the standard and idealized model of a uniform conical jet has worked well. However, recent afterglow observations of the brightest GRB observed to date are shedding new light on the jet structure, emission from which cannot be explained with the standard model. This added complexity also demands improvements in the existing theoretical models and tools to properly explain the afterglow emission arising from structured jets. The structure of the magnetic field, both in the jet material and the shocked external medium behind the collisionless shock launched by the jet, is still unclear. Afterglow linear polarization measurements are now providing new clues. In this talk, I will discuss the theory behind collisionless shocks propagating both inside the jet and ahead of the jet, and how one can use afterglow synchrotron emission arising from these two shocks to understand the shock microphysics and constrain the magnetic field and jet structure.