2019A&A...630A..94G

Context. Understanding the physics and geometry of accretion and ejection around super massive black holes (SMBHs) is important to understand the evolution of active galactic nuclei (AGN) and therefore of the large scale structures of the Universe.
Aims. We aim at providing a simple, coherent, and global view of the sub-parsec accretion and ejection flow in AGN with varying Eddington ratio, m, and black hole mass, M_BH.
Methods. We made use of theoretical insights, results of numerical simulations, as well as UV and X-ray observations to review the inner regions of AGN by including different accretion and ejection modes, with special emphasis on the role of radiation in driving powerful accretion disk winds from the inner regions around the central SMBH.
Results. We propose five m regimes where the physics of the inner accretion and ejection flow around SMBHs is expected to change, and that correspond observationally to quiescent and inactive galaxies; low luminosity AGN (LLAGN); Seyferts and mini-broad absorption line quasars (mini-BAL QSOs); narrow line Seyfert 1 galaxies (NLS1s) and broad absorption line quasars (BAL QSOs); and super-Eddington sources. We include in this scenario radiation-driven disk winds, which are strong in the high m, large M_BH regime, and possibly present but likely weak in the moderate m, small M_BH regime.
Conclusions. A great diversity of the accretion/ejection flows in AGN can be explained to a good degree by varying just two fundamental properties: the Eddington ratio m and the black hole mass M_BH, and by the inclusion of accretion disk winds that can naturally be launched by the radiation emitted from luminous accretion disks.