2025/06/02 by Jakub Podgorný, Podgorný, J. · 1 citation
Biochemistry, Genetics and Molecular Biology · Earth and Planetary Sciences · #FOS: Physical sciences #Geomagnetism and Paleomagnetism Studies #Geophysics and Gravity Measurements #High Energy Astrophysical Phenomena (astro-ph.HE) #High-pressure geophysics and materials
paper · doi:10.48550/arxiv.2506.01798
openalex publication_date 2025/06/02 · openalex created_date 2025/10/14 · openalex updated_date 2026/07/28
Motivated by the success of the IXPE mission, we elucidate what can be inferred about 3D matter structures forming about the equatorial plane of accreting compact objects from 0.1-100 keV linear polarization induced by non-relativistic large-scale reflection. We construct a model of an optically thick elevated axially symmetric reflecting medium with arbitrary ionization profile, representing the known diverse scattering environments: from thick winds and super-Eddington funnel structures formed around black holes and neutron stars, to Compton-thick dusty tori of active galactic nuclei and their broad line regions. We assume a central X-ray power-law source with an isotropic, cosine, and slab-corona emission distribution, including intrinsic polarization. The reprocessing is based on constant-density local reflection tables produced with a Monte Carlo method combined with detailed non-LTE radiative transfer, although we also show examples with classical (semi-)analytical reflection prescriptions. We conclude that varying ionization has a similarly strong impact on observed polarization as the observer's inclination and the skew and opening angle of the reflector's inner walls, altogether producing up to tens of % of reflected polarization both parallelly or perpendicularly to the projected axis, depending on the parameter values combination. After testing 3 different ad-hoc shapes of the reflector: a cone, an elliptical torus, and a bowl, we conclude that while in some configurations, their altered curvature produces more than 30% absolute difference in observed total polarization, in others, the adopted shape has a marginal impact. Lastly, we discuss the change of the observed polarization due to relaxing the optically thick assumption on equatorial winds and accreted matter, providing a continuous range of energy-dependent examples between the optically thick and thin scenarios.