X-ray polarimetry on-board HXMT

TL;DR

This paper discusses the design and potential of on-board X-ray polarimetry using micropixel gas detectors on the HXMT mission, aiming to measure polarization of celestial X-ray sources with moderate additional resources.

Contribution

It introduces a novel X-ray polarimeter design for HXMT, demonstrating its capability to measure polarization with limited additional resources, representing a potential breakthrough.

Findings

Design of X-ray telescopes with polarimeters for HXMT

Performance analysis showing capability to detect polarization

Potential for significant advancements in X-ray polarimetry

Abstract

The development of micropixel gas detectors, capable to image tracks produced in a gas by photoelectrons, makes possible to perform polarimetry of X-ray celestial sources in the focus of grazing incidence X-ray telescopes. HXMT is a mission by the Chinese Space Agency aimed to survey the Hard X-ray Sky with Phoswich detectors, by exploitation of the direct demodulation technique. Since a fraction of the HXMT time will be spent on dedicated pointing of particular sources, it could host, with moderate additional resources a pair of X-ray telescopes, each with a photoelectric X-ray polarimeter (EXP2, Efficient X-ray Photoelectric Polarimeter) in the focal plane. We present the design of the telescopes and the focal plane instrumentation and discuss the performance of this instrument to detect the degree and angle of linear polarization of some representative sources. Notwithstanding the limited resources, the proposed instrument can represent a breakthrough in X-ray Polarimetry.