LIGHT-BENDING SCENARIO FOR ACCRETING BLACK HOLES IN X-RAY POLARIMETRY

Journal Article · Sun Apr 10 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/731/1/75· OSTI ID:21574742

Dovciak, M; Karas, V ^[1]; Muleri, F ^[2]; Goosmann, R W ^[3]; Matt, G ^[4]

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1. Astronomical Institute, Academy of Sciences, BocnI II, CZ-14131 Prague (Czech Republic)
2. Istituto di Astrofisica Spaziale e Fisica Cosmica, Via del Fosso del Cavaliere 100, I-00133 Rome (Italy)
3. Observatoire Astronomique de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg (France)
4. Dipartimento di Fisica, Universita degli Studi 'Roma Tre', Via della Vasca Navale 84, I-00146 Rome (Italy)

We discuss a model of an X-ray illuminating source above an accretion disk of a rotating black hole. Within the so-called lamp-post scheme we compute the expected (observed) polarization properties of the radiation reaching an observer. We explore the dependences on model parameters, employing Monte Carlo radiation transfer computations of the X-ray reflection on the accretion disk and taking general relativity effects into account. In particular, we discuss the role of the black hole spin, of the observer viewing angle, and of the primary X-ray source distance from the black hole. We give several examples of the resulting polarization degree for two types of exemplary objects-active galactic nuclei and Galactic black holes. In order to assess potential observability of the polarization features, we assume the sensitivity of the proposed New Hard X-ray Mission (NHXM). We examine the energy range from several keV to {approx}50 keV, so the iron line complex and the Compton hump are included in our model spectra. We find the resultant polarization degree to increase at the higher end of the studied energy band, i.e., at {approx}>20 keV. Thus, the best results for polarimetry of reflection spectra should be achieved at the Compton hump energy region. We also obtain a higher polarization degree for large spin values of the black hole, small heights of the primary source, and low inclination angles of the observer.

• OSTI ID: 21574742
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 731; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
ANGULAR MOMENTUM
BLACK HOLES
CALCULATION METHODS
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
DISTANCE
GALAXIES
GALAXY NUCLEI
MONTE CARLO METHOD
PARTICLE PROPERTIES
POLARIMETRY
POLARIZATION
SPIN
X-RAY GALAXIES