A physical model for radiative, convective dusty disk in AGN

TL;DR

This paper presents a physical model of dusty accretion disks in AGNs, showing how radiation pressure and convection influence their structure and linking to existing AGN models.

Contribution

It introduces a detailed physical model of dusty AGN disks considering radiation pressure and convection, integrating previous theories into a unified framework.

Findings

Radiation pressure significantly affects disk vertical structure.

Disks can transition from thin to slim configurations.

Model supports the 'failed wind' and 'compact torus' scenarios.

Abstract

An accretion disk in an Active Galactic Nucleus (AGN) harbors and shields dust from external illumination: at the mid-plane of the disk around a $M_{{\rm BH}}=10^{7}M_{\odot}$ black hole, dust can exist at $0.1$pc from the black hole, compared to 0.5pc outside of the disk. We construct a physical model of a disk region approximately located between the radius of dust sublimation at the disk mid-plane and the radius at which dust sublimes at the disk surface. Our main conclusion is that for a wide range of model parameters such as local accretion rate and/or opacity, the accretion disk's own radiation pressure on dust significantly influences its vertical structure. In addition to being highly convective, such a disk can transform from geometrically thin to slim. Our model fits into the narrative of a "failed wind" scenario of Czerny & Hryniewicz (2011) and the "compact torus" model of Baskin & Laor (2018), incorporating them as variations of the radiative dusty disk model.