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Accreting black holes via X-ray polarimetry
Mikušincová, Romana ; Svoboda, Jiří (advisor) ; Matt, Giorgio (referee)
Black hole spin is an essential parameter, for it provides us with the infor- mation on the black hole formation and growth. In this Thesis, we simulated observations for an upcoming X-ray polarimetric mission IXPE (Imaging X- ray Polarimetry Explorer) with the aim to study the robustness of black hole spin and inclination measured via X-ray polarimetry. To simulate polarization spectra, we used a multicolor blackbody emission model accounting for thermal radiation from the accretion disk. For the case of maximally rotating black hole (spin a = 0.998), we were able to reconstruct both spin and inclination of the system with a high precision (∆a ≤ 0.2 for spin and ∆θ ≤ 15 deg for inclination). For less rotating black holes, the spin was correctly recovered, but with a large uncertainty. The inclination is well constrained for any spin value. We conclude that polarimetric measurements will be useful to make independent black hole spin measurements, that would be compared with the spectral-fitting and timing methods. Therefore, X-ray polarimetric missions will be highly desirable. 1
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X-ray spectroscopy of polar-scattered Seyfert 1 galaxies
Mikušincová, Romana ; Svoboda, Jiří (advisor) ; Horák, Jiří (referee)
In this thesis we present a spectral re-analysis of the Fairall 51 galaxy. It is optically a Seyfert 1 galaxy. It does, however, show a very strong polarization in the optical spectrum and as this feature is not characteristic for Seyfert 1 objects, this galaxy may represent a borderline object between Seyfert 1 and Seyfert 2 galaxies and provide with valuable information about the structure of Active Galactic Nuclei. We studied two archival sets of observations performed in September 2005 and March 2006 by the European satellite XMM-Newton and four observations performed in September 2013 by the Japanese observatory Suzaku. It follows from the spectral analysis that there are at least two or three ionized absorbers in the studied AGN. Based on the spectral variability, we were also able to estimate the location of the variable absorber which appears to be 3 to 60 light days from the central engine, which indicates its origin in the Broad Line Region. 1
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