2016/04/12 by Daisuke Namekata, Masayuki Umemura · 60 citations
Engineering · Physics and Astronomy · #Accretion (finance) #Active galactic nucleus #Astrophysical Phenomena and Observations #Astrophysics #Eddington luminosity #Galaxies: Formation, Evolution, Phenomena #Galaxy #Heat Transfer Mechanisms #Optics #Outflow #Photon #Physics #RADIUS #Radiation pressure #Radiative transfer #Sublimation (psychology) #Supermassive black hole #astro-ph.GA #astro-ph.HE
paper · pdf · doi:10.1093/mnras/stw862
published in Monthly Notices of the Royal Astronomical Society 460(1), 980-1018 (Oxford University Press) · 40 pages, 33 figures, 7 tables; accepted for publication in Monthly Notices of the Royal Astronomical Society
arxiv created 2016/04/12 · openalex publication_date 2016/04/17 · arxiv updated 2016/04/27 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We explore the gas dynamics near the dust sublimation radius of active galactic nucleus (AGN). For the purpose, we perform axisymmetric radiation hydrodynamic simulations of a dusty gas disc of radius ≈1 pc around a supermassive black hole of mass 107 M⊙ taking into account (1) anisotropic radiation of accretion disc, (2) X-ray heating by corona, (3) radiative transfer of infrared (IR) photons re-emitted by dust, (4) frequency dependence of direct and IR radiations, and (5) separate temperatures for gas and dust. As a result, we find that for Eddington ratio ≈0.77, a nearly neutral, dense (|≈ 10^6--8 \mathrmcm-3|), geometrically thin (h/r < 0.06) disc forms with a high-velocity (≈200 ∼ 3000 km s−1) dusty outflow launched from the disc surface. The disc temperature is determined by the balance between X-ray heating and various cooling, and the disc is almost supported by thermal pressure. Contrary to Krolik (2007), the radiation pressure by IR photons is not effective to thicken the disc, but rather compresses it. Thus, it seems difficult for a radiation-supported, geometrically thick, obscuring torus to form near the dust sublimation radius as far as the Eddington ratio is high (∼1). The mass outflow rate is |0.05--0.1 M\odot yr-1| and the column density of the outflow is NH ≲ 1021 cm−2. To explain observed type-II AGN fraction, it is required that outflow gas is extended to larger radii (r ≳ 10 pc) or that a denser dusty wind is launched from smaller radii (r ∼ 104 Rg).