2015/02/12 by Ya-Di Xu, Yadi Xu
Physics and Astronomy · #Accretion (finance) #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Corona (planetary geology) #Emission spectrum #Galaxies: Formation, Evolution, Phenomena #Galaxy #Luminosity #Luminous infrared galaxy #Optics #Physics #Radiation #Radio galaxy #Spectral line #astro-ph.HE
paper · pdf · doi:10.1093/mnras/stv290
8 pages, accepted by MNRAS
arxiv created 2015/02/12 · openalex publication_date 2015/03/17 · arxiv updated 2015/06/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
In the unification scheme for active galactic nuclei, type 1 Seyfert galaxies and type 2 Seyfert galaxies are thought to be intrinsically the same but viewed at different angles. However, the Fe Kα emission line luminosity of type 1 Seyfert galaxies was found on average to be about twice that of type 2 Seyfert galaxies for a given X-ray continuum luminosity in previous work. We construct an accretion disc-corona model in which a fraction of the energy dissipated in the disc is extracted to heat the corona above the disc. The radiation transfer equation with Compton scattering processes is an integro-differential equation, which is solved numerically for the corona with a parallel plane geometry. We find that the specific intensity of X-ray radiation from the corona changes little with the viewing angle θ when θ is small (nearly face-on), and it is sensitive to θ if the viewing angle is large (θ ≳ 40°). The radiation from the cold disc, mostly in infrared, optical and UV bands, is almost proportional to cos θ when θ ≲ 40°, while it decreases more rapidly than cos θ when θ ≳ 40° because of strong absorption in the corona in this case. For Seyfert galaxies, the Fe Kα line may probably be emitted from the disc irradiated by the X-ray continuum emission. The observed equivalent width difference between type 1 Seyfert galaxies and type 2 Seyfert galaxies can be reproduced by our model calculations, provided the type 1 Seyfert galaxies are observed nearly face-on and the average inclination angle of type 2 Seyfert galaxies is ∼65°.