학술논문
Observations of a GX 301-2 Apastron Flare with the X-Calibur Hard X-Ray Polarimeter Supported by NICER, the Swift XRT and BAT, and Fermi GBM
Document Type
Working Paper
Author
Abarr, Q.; Baring, M.; Beheshtipour, B.; Beilicke, M.; deGeronimo, G.; Dowkontt, P.; Errando, M.; Guarino, V.; Iyer, N.; Kislat, F.; Kiss, M.; Kitaguchi, T.; Krawczynski, H.; Lanzi, J.; Li, S.; Lisalda, L.; Okajima, T.; Pearce, M.; Press, L.; Rauch, B.; Stuchlik, D.; Takahashi, H.; Tang, J.; Uchida, N.; West, A.; Jenke, P.; Krimm, H.; Lien, A.; Malacaria, C.; Miller, J. M.; Wilson-Hodge, C.
Source
Subject
Language
Abstract
The accretion-powered X-ray pulsar GX 301-2 was observed with the balloon-borne X-Calibur hard X-ray polarimeter during late December 2018, with contiguous observations by the NICER X-ray telescope, the Swift X-ray Telescope and Burst Alert Telescope, and the Fermi Gamma-ray Burst Monitor spanning several months. The observations detected the pulsar in a rare apastron flaring state coinciding with a significant spin-up of the pulsar discovered with the Fermi GBM. The X-Calibur, NICER, and Swift observations reveal a pulse profile strongly dominated by one main peak, and the NICER and Swift data show strong variation of the profile from pulse to pulse. The X-Calibur observations constrain for the first time the linear polarization of the 15-35 keV emission from a highly magnetized accreting neutron star, indicating a polarization degree of (27+38-27)% (90% confidence limit) averaged over all pulse phases. We discuss the spin-up and the X-ray spectral and polarimetric results in the context of theoretical predictions. We conclude with a discussion of the scientific potential of future observations of highly magnetized neutron stars with the more sensitive follow-up mission XL-Calibur.
Comment: Accepted for publication in the Astrophysical Journal. 20 pages, 19 figures, 4 tables
Comment: Accepted for publication in the Astrophysical Journal. 20 pages, 19 figures, 4 tables