Gamma-Ray Polarimetry

TL;DR

Gamma-ray polarimetry has great scientific potential but faces technical challenges; recent advancements and upcoming instruments like POLAR-2 and COSI promise significant progress in measuring high-energy photon polarization.

Contribution

This paper reviews the fundamental concepts and experimental methods of gamma-ray polarimetry, highlighting recent technological developments and upcoming missions that aim to improve polarization measurements.

Findings

Development of second-generation GRB polarimeters POLAR-2 and COSI.

Recent technological progress enhances prospects for astrophysical gamma-ray polarization detection.

Review of scattering and pair production polarimetry techniques for high-energy photons.

Abstract

While the scientific potential of high-energy X-ray and gamma-ray polarimetry has long been recognized, measuring the polarization of high-energy photons is challenging. To date, there has been very few significant detections from an astrophysical source. However, recent technological developments raise the possibility that this may change in the not-too-distant future. Significant progress has been made in the development of Gamma-ray Burst (GRB) polarimeters and polarization sensitive Compton telescopes. A second-generation dedicated GRB polarimeter, POLAR-2, is under development for launch in 2024, and COSI a second-generation polarization sensitive Compton Telescope has been selected by NASA for launch in 2025. This chapter reviews basic concepts and experimental approaches of scattering polarimetry of hard X-rays to MeV {\gamma}-rays, and pair production polarimetry of higher-energy photons