The Next-Generation Balloon-Borne Hard X-ray Polarimeter XL-Calibur
Abstract
X-ray polarimetry promises geometrical information about compact astrophysical objects such as accreting black holes and neutron stars that are too small to be imaged at any wavelength. X-Calibur is a balloon-borne hard X-ray polarimeter covering the 20-40keV energy range consisting of an 8m long optical bench carrying the InFOCμS hard X-ray mirror, and a scattering polarimeter at its focal point.Here we present a powerful follow-up mission, XL-Calibur, with a 6-times greater sensitivity. XL-Calibur will consist of an enhanced scattering polarimeter based on the X-Calibur design in the focal plane of the spare hard X-ray mirror of the Japanese Hitomi mission. The 12m-focal-length mirror increases the effective area in the core energy region from 20-40keV by a factor of 4 and even more at higher energies, increasing the bandwidth of XL-Calibur as compared to X-Calibur. Furthermore, the polarimeter will use a more compact design and thinner CZT detectors, significantly reducing the background. We conclude with a discussion of the neutron star, accretion physics, and fundamental physics constraints that can be obtained with this mission.
- Publication:
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AAS/High Energy Astrophysics Division
- Pub Date:
- March 2019
- Bibcode:
- 2019HEAD...1710979K