From Thin to Thick: The Impact of X-ray Irradiation on Accretion Disks in AGN

Abstract

We argue that the X-ray and UV flux illuminating the parsec-scale accretion disk around luminous active galactic nuclei (AGN) is super-Eddington with respect to the local far-infrared dust opacity. The far infrared opacity may be larger than in the interstellar medium of the Milky Way due to a combination of supersolar metallicity and the growth of dust grains in the dense accretion disk. Because of the irradiating flux, the outer accretion disk puffs up with a vertical thickness $h\sim R$. This provides a mechanism for generating a geometrically thick obscuring region from an intrinsically thin disk. We find obscuring columns $\sim 10^{22}-10^{23}{\mathrm{cm}}^{-2}$, in reasonable agreement with observations.

8 pages, 4 figures, accepted to ApJ. changes made from suggestion by the referee

References in corpus (8)

• High Resolution Submillimeter Constraints on Circumstellar Disk Structure
• On the X-ray, optical emission line and black hole mass properties of local Seyfert galaxies
• Emission-line Diagnostics of Low Metallicity AGN
• The Star-Forming Torus and Stellar Dynamical Black Hole Mass in the Seyfert 1 Nucleus of NGC3227
• The distribution of silicate strength in Spitzer spectra of AGNs and ULIRGs
• Deep Mid-Infrared Silicate Absorption as a Diagnostic of Obscuring Geometry Toward Galactic Nuclei
• Chemical Abundances in AGN Environment: X-Ray/UV Campaign on the MRK 279 Outflow
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