Title: Polarization Measurements of Prompt Gamma- and X-ray emission in Gamma Ray Bursts (and SGR Flares) with INTEGRAL
Proposal ID: 0120139
Subject category: Others
Principal investigator: Kouveliotou
Institute: NASA/MSFC
Abstract
We propose here to use the Compton mode for IBIS to measure X-ray and gamma-ray polarization -a not very
well advertised capability of Integral- in the prompt gamma-and X-ray emission of Bright Gamma Ray Bursts
and in the first pulse of Soft Gamma Repeater flares. Polarization measurements at photon energies greater
than 10 keV have never been performed in GRBs due to the lack of adequately sensitive instruments, nor has
polarization been measured in GRB prompt emission in any wavelength. Almost all gamma-ray emission
mechanisms, however, will produce polarized photons in various degrees, especially the synchrotron mechanism
thought to operate in GRBs. Determining the GRB polarization level will be a ground-breaking step both in
observational and theoretical high-energy astrophysics. It will allow us to determine the nature of the GRB
central engine, the origin of the magnetic fields in GRBs, and constrain the acceleration mechanism of
electrons in relativistic shocks.