Polarized radiation from the spreading layer of the weakly magnetized neutron stars

Abstract

Observations show that the X-ray emission of the accreting weakly magnetized neutron stars is polarized. Here, we develop a theoretical model, where we assume the emission of the accreting neutron star coming from the spreading layer, the extension of the boundary between the disk and the neutron star surface onto the surface. We then calculate the Stokes parameters of the emission accounting for relativistic aberration and gravitational light bending in the Schwarzschild metric. We show that regardless of the geometry, for the spreading layer, we cannot expect the polarization degree to be higher than 1.5%. Our results have implications with regard to the understanding of the X-ray polarization from weakly magnetized neutron stars observed with the Imaging X-ray Polarimetry Explorer and the future enhanced X-ray Timing and Polarimetry mission.

9 pages, 7 figures

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Cited by in corpus (6)

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• X-ray spectropolarimetric characterization of the Z-source GX 340+0 in the normal branch
• IXPE view of the Sco-like source GX 349+2 in the normal branch
• The detection of high X-ray polarization from an accretion disc corona source and its modelling via Monte Carlo radiation transfer simulation
• X-ray polarization of Z-type neutron star low-mass X-ray binaries -- II. Spectropolarimetric analysis
• Fast and accurate analytical formulas for light propagation in general static, spherically symmetric spacetimes