Spectral and polarization properties of reflected X-ray emission from black hole accretion discs

0553049 - ASÚ 2023 RIV GB eng J - Journal Article
Podgorný, Jakub - Dovčiak, Michal - Marin, F. - Goosmann, R. W. - Rózanska, A.
Spectral and polarization properties of reflected X-ray emission from black hole accretion discs.
Monthly Notices of the Royal Astronomical Society. Roč. 510, č. 4 (2022), s. 4723-4735. ISSN 0035-8711. E-ISSN 1365-2966
R&D Projects: GA ČR(CZ) GX21-06825X
Institutional support: RVO:67985815
Keywords : active galactic nuclei * fluorescent iron lines * k-alpha line
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 4.8, year: 2022
Method of publishing: Limited access
https://doi.org/10.1093/mnras/stab3714

In this work, we present a yet missing piece in the global polarization models of black hole accretion discs. We compute the reflected X-ray emission from the disc in a local co-moving frame using (1) the radiative transfer code TITAN to obtain the ionization structure of the disc and (2) the Monte Carlo code STOKES that incorporates the physics of absorption, re-emission, and Compton scattering to produce a complete spectropolarimetric output. We present the final Stokes parameters I, Q, and U for a set of photon-indices of the incident primary power-law radiation, the disc ionization parameters, incident and emission angles, for three independent polarization states of the incident coronal X-ray photons with a sufficient resolution in energy to allow for sharp discussion of spectral and polarization properties. We show that the spectral component matches well literature predictions. The polarization degree and angle are in agreement with analytical approximations previously appearing in reflection models and we demonstrate that the polarized reflected X-ray emission can be, locally, quite large in the 2-12 keV band.
Permanent Link: http://hdl.handle.net/11104/0330941