NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Parsec-Scale Accretion and Winds Irradiated by a QuasarWe present numerical simulations of properties of a parsec-scale torus exposed to illumination by the central black hole in an active galactic nucleus (AGN). Our physical model allows to investigate the balance between the formation of winds and accretion simultaneously. Radiation-driven winds are allowed by taking into account radiation pressure due to UV and IR radiation along with X-ray heating and dust sublimation. Accretion is allowed through angular momentum transport and the solution of the equations of radiative, viscous radiation hydrodynamics. Our methods adopt flux-limited diffusion radiation hydrodynamics for the dusty, infrared pressure driven part of the flow, along with X-ray heating and cooling. Angular momentum transport in the accreting part of the flow is modeled using effective viscosity. Our results demonstrate that radiation pressure on dust can play an important role in shaping AGN obscuration. For example, when the luminosity illuminating the torus exceeds L greater than 0.01 L(sub Edd), where L(sub Edd) is the Eddington luminosity, we find no episodes of sustained disk accretion because radiation pressure does not allow a disk to form. Despite the absence of the disk accretion, the flow of gas to smaller radii still proceeds at a rate 10(exp -4)-10(exp -1)M dot yr(exp -1) through the capturing of the gas from the hot evaporative flow, thus providing a mechanism to deliver gas from a radiation-pressure dominated torus to the inner accretion disk. As L L(sub edd) increases, larger radiation input leads to larger torus aspect ratios and increased obscuration of the central black hole. We also find the important role of the X-ray heated gas in shaping the obscuring torus.
Document ID
20170002401
Document Type
Reprint (Version printed in journal)
Authors
Dorodnitsyn, A. (Maryland Univ. College Park, MD, United States)
Kallman, T. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Proga, D. (Nevada Univ. Las Vegas, NV, United States)
Date Acquired
March 21, 2017
Publication Date
March 4, 2016
Publication Information
Publication: The Astrophysical Journal
Volume: 819
Issue: 2
ISSN: 0004-637X
Subject Category
Astrophysics
Report/Patent Number
GSFC-E-DAA-TN40235
Funding Number(s)
CONTRACT_GRANT: 10-ATP10-0171
CONTRACT_GRANT: NNX11AI96G
Distribution Limits
Public
Copyright
Other
Keywords
accretion disks - galaxies: active - galaxies: Seyfert - radiation: dynamics
ccretion