Structure of an Absorbing Medium in the Nucleus of the Galaxy Mrk 417 Based on NuSTAR and Swift/Bat Data
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STRUCTURE OF AN ABSORBING MEDIUM IN THE NUCLEUS OF THE GALAXY Mrk 417 BASED ON NuSTAR AND Swift/BAT DATA
O.V. Kompaniiets and A. A. Vasylenko
We present the results of X-ray spectral analysis of the Seyfert type 2 galaxy Mrk 417 ( z | 0.0327 ) based on data from the NuSTAR (3-60 keV) and Swift/BAT (14-150 keV) space observatories. The spectrum from the NuSTAR observatory is well described by a basic power-law model with neutral absorption and an additional reflection component from a cold neutral medium (power-law index * 1.6300..10 11 , absorption N H EWFe KD
23 -2 3.22 00..41 39 10 cm ). A narrow Fe K D emission line with an equivalent width
115 12 eV is present and indicates a moderate density of the medium in which this line is
formed. The NuSTAR data together with the Swift/BAT data were analyzed using the more complicated physical models MYTorus and BNTorus. In the first case a power-law index *MYTorus absorption along the line of sight of N H l.o.s yields a power-law index of N H l.o.s
*BNTorus
1.6800..09 09 and an
23 -2 3.36 00..04 07 10 cm were obtained. The BNTorus model
1.7500..09 09 and an absorption along the line of sight of
23 -2 3.72 00..49 39 10 cm . These results provide an estimate of the covering factor for the gas-dust
43 torus of f c | 0.29 0.34 and derive absorption-corrected X-ray luminosity of L intr 2-10 keV ~ 3.16 10
erg/s. Additional analysis of the observational data in the near IR indicates that the covering factor may even be smaller, at fc~0.12. These results indicate that the gas-dust torus is most likely compressed along the vertical and has preferably a ring-like geometry. Keywords: active galactic nuclei: gas-dust torus: Mrk 417: x-radiation
Main Astronomical Observatory, National Academy of Sciences of Ukraine, Kiev, Ukraine; e-mail: [email protected]
Original article submitted January 27, 2020; accepted for publication June 24, 2020. Translated from Astrofizika, Vol. 63, No. 3, pp. 345-361 (August 2020). 0571-7256/19/6303-0307 ©2020 Springer Science+Business Media, LLC
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1. Introduction
The structure of active galactic nuclei (AGN) is described by a unified scheme [1]: at the center of an AGN there is a supermassive black hole with an accretion disk around which a gas-dust torus is located. The gas-dust torus is one of the key elements of the unified scheme and, depending on the angle of inclination, is responsible for the classification of Seyfert galaxies. The interaction of the primary radiation from the corona of the accretion disk with matter in the torus leads to the formation of a reflection spectrum [2-4]. The characteristic features of the reflection spectrum are emission lines of iron and other elements, in particular neutral or ionized iron FeK D with energies of 6.4 and 6.7 keV, as well as a characteristic hump in the continuum spectrum at an energy
of ~20-40 keV. The combined spectrum of the reflected and primary components, modified by absorption. is used to determine the characteristics and geometry of the gas-dus
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