POLAR-2, the next generation of GRB polarization detector

TL;DR

POLAR-2 is an advanced gamma-ray burst polarimeter designed to improve measurement accuracy and detect faint GRBs, building on the success of the POLAR mission and aiming for deployment on the China Space Station in 2025.

Contribution

POLAR-2 introduces a high-precision, larger-area polarimeter with extended energy range, enhancing GRB polarization measurements and enabling detection of very faint GRBs.

Findings

POLAR measured low polarization in 14 GRBs with complex time evolution.

POLAR-2 will significantly improve measurement accuracy and sensitivity.

The instrument is scheduled for deployment on the China Space Station in 2025.

Abstract

The POLAR-2 Gamma-Ray Burst (GRB) Polarimetry mission is a follow-up to the successful POLAR mission. POLAR collected six months of data in 2016-2017 on board the Tiangong-2 Chinese Space laboratory. From a polarization study on 14 GRBs, POLAR measured an overall low polarization and a hint for an unexpected complexity in the time evolution of polarization during GRBs. Energy-dependent measurements of the GRB polarization will be presented by N. de Angelis in GA21-09 (August 2nd). These results demonstrate the need for measurements with significantly improved accuracy. Moreover, the recent discovery of gravitational waves and their connection to GRBs justifies a high-precision GRB polarimeter that can provide both high-precision polarimetry and detection of very faint GRBs. The POLAR-2 polarimeter is based on the same Compton scattering measurement principle as POLAR, but with an extended energy range and an order of magnitude increase in total effective area for polarized events. Proposed and developed by a joint effort of Switzerland, China, Poland and Germany, the device was selected for installation on the China Space Station and is scheduled to start operation for at least 2 years in 2025.