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Coronal accretion: the power of X-ray emission in AGN

Published online by Cambridge University Press:  07 March 2016

B.-F. Liu
Affiliation:
National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012, China email: bfliu@nao.cas.cn
R. E. Taam
Affiliation:
Academia Sinica Institute of Astronomy and Astrophysics-TIARA, P.O. Box 23-141, Taipei, 10617Taiwan
E. Qiao
Affiliation:
National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012, China email: bfliu@nao.cas.cn
W. Yuan
Affiliation:
National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012, China email: bfliu@nao.cas.cn
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Abstract

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The optical/UV and X-ray emissions in luminous AGN are commonly believed to be produced in an accretion disk and an embedded hot corona respectively. We explore the possibility that a geometrically thick coronal gas flow, which is supplied by gravitational capture of interstellar medium or stellar wind, condenses partially to a geometrically thin cold disk and accretes via a thin disk and a corona onto the supermassive black hole. We found that for mass supply rates less than about 0.01 (expressed in Eddington units), condensation does not occur and the accretion flow takes the form of a corona/ADAF. For higher mass supply rates, corona gas condenses to the disk. As a consequence, the coronal mass flow rate decreases and the cool mass flow rate increases towards the black hole. Here the thin disk is characterized by the condensation rate of hot gas as it flows towards the black hole. With increase of mass supply rate, condensation becomes more efficient, while the mass flow rate of the coronal gas attains values of order 0.02 in the innermost regions of the disk, which can help to elucidate the production of strong X-ray with respect to the optical and ultraviolet radiation in high luminosity AGN.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2016 

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