Spectropolarimetric observations of active galactic nuclei with the 6-m BTA telescope

Afanasiev, V. L.; Borisov, N. V.; Gnedin, Yu. N.; Natsvlishvili, T. M.; Piotrovich, M. Yu.; Buliga, S. D.

doi:10.1134/s106377371105001x

Cited by 29 publications

(33 citation statements)

References 17 publications

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“…The estimate of inclination angle can be obtained from the polarimetric observations in the framework of the theory of radiative transfer of polarized radiation (Chandrasekhar 1950;Sobolev 1963). We used for estimate of µ the results of polarimetric observations obtained by Berriman et al (1990); Smith et al (2002); Afanasiev et al (2011). The results of our calculations of the radiative efficiency ε(a) and determined values of the spin are presented in the Table 1.…”

Section: Discussionmentioning

confidence: 99%

“…The value of cos i for (1) is obtained using Eqs. (5)- (7), for (2) is obtained using polarimetric data from Smith et al (2002), for (3) is obtained from Berriman et al (1990), for (4) is obtained from Afanasiev et al (2011). …”

Section: Basic Equationsmentioning

confidence: 99%

“…Determination of µ is playing an important part in Eq.(2). The information on µ was obtained from polarimetric data from Berriman et al (1990);Webb et al (1993); Smith et al (2002); Afanasiev et al (2011);Marin (2016). The totality of these data allows us to determine the radiation efficiency ε(a) and then the spin value a.…”

Section: Basic Equationsmentioning

confidence: 99%

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Constraints on spin of a supermassive black hole in quasars with big blue bump

Piotrovich

Gnedin

Natsvlishvili

et al. 2017

Astrophys Space Sci

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We determined the spin value of supermassive black hole (SMBH) in active galactic nuclei (AGN) with investigated ultraviolet-to-optical spectral energy distribution, presented in the sample of Shang et al. (2005). The estimates of the spin values have been produced at the base of the standard geometrically thin accretion disk model and with using the results of the polarimetric observations. The polarimetric observations are very important for determining the inclination angle of AGN disk. We presented the results of our determinations of the radiation efficiency of the accretion flow and values of the spins of SMBHs, that derives the coefficient of radiation efficiency. The majority of SMBHs of AGNs from Shang et al. (2005) sample are to be the Kerr black holes with the high spin value.

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Section: Discussionmentioning

confidence: 99%

Section: Basic Equationsmentioning

confidence: 99%

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Constraints on spin of a supermassive black hole in quasars with big blue bump

Piotrovich

Gnedin

Natsvlishvili

et al. 2017

Astrophys Space Sci

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“…Results for spectropolarimetric observations of a number of AGNs on the SAO 6-m telescope are presented in [12]. These results were used in [13] to estimate the spins of the central supermassive black holes in the observed AGNs.…”

Section: Observations and Reductionmentioning

confidence: 98%

Spectral distribution of the polarized radiation from standard accretion disks in Active Galactic Nuclei: Observational analysis

et al. 2014

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Spectropolarimetric observations of a number of Active Galactic Nuclei obtained using the SCORPIO-2 aperture focal reducer installed on the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences are used to estimate physical parameters of these objects. The measured polarization and its wavelength dependence are consistent with the expectations of a standard accretion-disk model taking into account the effect of Faraday depolarization over the mean free path of the emitted photons. Estimates of the magnetic field in the accretion disk near the innermost stable orbit and the spin of the accreting central black hole are obtained. It is concluded that supermassive black holes with standard accretion disks and equal magnetic and radiative pressures are primarily Kerr black holes.

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“…We considered the induction equation in a kinematic approximation, where the kinetic energy of the gas is much greater than the energy of the magnetic field (ρ gas U 2 /2 B 2 /(8π)), where ρ gas is the density of the disk matter. The possible realization of this situation in a standard accretion disk was considered in [18], based on an analysis of data on the wavelength dependence of the observed degree of polarization for a number of active galactic nuclei [19]. In this approximation, we can neglect the dependence of the gas velocity on the magnetic field.…”

Section: Induction Equationmentioning

confidence: 99%

The magnetic-field structure in a stationary accretion disk

et al. 2016

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The magnetic-field structure in regions of stationary, planar accretion disks around active galactic nuclei where general-relativistic effects can be neglected (from 10 to 200 gravitational radii) is considered. It is assumed that the magnetic field in the outer edges of the disk, which forms in the magnetosphere of the central black hole during the creation of the relativisitic jets, corresponds to the field of a magnetic dipole perpendicular to the plane of the disk. In this case, the azimuthal field component B ϕ in the disk arises due to the presence of the radial field B ρ and the azimuthal velocity component U ϕ . The value of the magnetic field at the inner radius of the disk is taken to correspond to the solution of the induction equation in a diffusion approximation. Numerical solutions of the induction equation are given for a number of cases.

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Spectropolarimetric observations of active galactic nuclei with the 6-m BTA telescope

Cited by 29 publications

References 17 publications

Constraints on spin of a supermassive black hole in quasars with big blue bump

Constraints on spin of a supermassive black hole in quasars with big blue bump

Spectral distribution of the polarized radiation from standard accretion disks in Active Galactic Nuclei: Observational analysis

The magnetic-field structure in a stationary accretion disk

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