The PoGO+ view on Crab off-pulse hard X-ray polarization
Abstract
The linear polarization fraction (PF) and angle of the hard X-ray emission from the Crab provide unique insight into high-energy radiation mechanisms, complementing the usual imaging, timing, and spectroscopic approaches. Results have recently been presented by two missions operating in partially overlapping energy bands, PoGO+ (18-160 keV) and AstroSat CZTI (100-380 keV). We previously reported PoGO+ results on the polarization parameters integrated across the light curve and for the entire nebula-dominated off-pulse region. We now introduce finer phase binning, in light of the AstroSat CZTI claim that the PF varies across the off-pulse region. Since both missions are operating in a regime where errors on the reconstructed polarization parameters are non-Gaussian, we adopt a Bayesian approach to compare results from each mission. We find no statistically significant variation in off-pulse polarization parameters, neither when considering the mission data separately nor when they are combined. This supports expectations from standard high-energy emission models.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 2018
- DOI:
- arXiv:
- arXiv:1802.07775
- Bibcode:
- 2018MNRAS.477L..45C
- Keywords:
-
- instrumentation: polarimeters;
- methods: statistical;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 6 pages, 3 figures, 5 tables. Accepted for publication in MNRAS Letters