Calibration and performance studies of the balloon-borne hard X-ray polarimeter PoGO+

Abstract

Polarimetric observations of celestial sources in the hard X-ray band stand to provide new information on emission mechanisms and source geometries. PoGO+ is a Compton scattering polarimeter (20-150 keV) optimised for the observation of the Crab (pulsar and wind nebula) and Cygnus X-1 (black hole binary), from a stratospheric balloon-borne platform launched from the Esrange Space Centre in summer 2016. Prior to flight, the response of the polarimeter has been studied with polarised and unpolarised X-rays allowing a Geant4-based simulation model to be validated. The expected modulation factor for Crab observations is found to be $M_{\mathrm{Crab}}=(41.75\pm 0.85)\%$, resulting in an expected Minimum Detectable Polarisation (MDP) of $7.3\%$ for a 7 day flight. This will allow a measurement of the Crab polarisation parameters with at least $5\sigma$ statistical significance assuming a polarisation fraction $\sim 20\%$ $-$ a significant improvement over the PoGOLite Pathfinder mission which flew in 2013 and from which the PoGO+ design is developed.

arXiv commentAccepted for publication in Nuclear Inst. and Methods in Physics Research, A

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Cited by in corpus (7)

• Accretion geometry of the black-hole binary Cygnus X-1 from X-ray polarimetry
• The PoGO+ Balloon-Borne Hard X-ray Polarimetry Mission
• Science prospects for SPHiNX - a small satellite GRB polarimetry mission
• The PoGO+ view on Crab off-pulse hard X-ray polarisation
• PoGO+ polarimetric constraint on the synchrotron jet emission of Cygnus X-1
• Signatures of Compact Halos of Sterile-Neutrino Dark Matter
• Gamma-ray burst localisation strategies for the SPHiNX hard X-ray polarimeter