Dynamics of Rotating Accretion Flows Irradiated by a Quasar

TL;DR

This study explores how rotation, radiation temperature, and background radiation influence the complex, dynamic accretion flows around supermassive black holes, revealing effects on flow structure, variability, and black hole feeding rates.

Contribution

It extends previous non-rotating flow models by including rotation, variable radiation temperature, and background radiation, showing their impact on flow dynamics and stability.

Findings

Rotation reduces outflow collimation and mass flux.

Position-dependent radiation temperature can reverse inflow to outflow.

Quasar radiation significantly decreases black hole accretion rates.

Abstract

We study the axisymmetric, time-dependent hydrodynamics of rotating flows that are under the influence of supermassive black hole gravity and radiation from an accretion disk surrounding the black hole. This work is an extension of the earlier work presented by Proga, where nonrotating flows were studied. Here, we consider effects of rotation, a position-dependent radiation temperature, density at large radii, and uniform X-ray background radiation. As in the non-rotating case, the rotating flow settles into a configuration with two components (1) an equatorial inflow and (2) a bipolar inflow/outflow with the outflow leaving the system along the pole. However, with rotation the flow does not always reach a steady state. In addition, rotation reduces the outflow collimation and the outward flux of mass and kinetic energy. Moreover rotation increases the outward flux of the thermal energy and can lead to fragmentation and time-variability of the outflow. We also show that a position-dependent radiation temperature can significantly change the flow solution. In particular, the inflow in the equatorial region can be replaced by a thermally driven outflow. Generally, as it have been discussed and shown in the past, we find that self-consistently determined preheating/cooling from the quasar radiation can significantly reduce the rate at which the central BH is fed with matter. However, our results emphasize also a little appreciated feature. Namely, quasar radiation drives a non-spherical, multi-temperature and very dynamic flow. These effects become dominant for luminosities in excess of 0.01 of the Eddington luminosity.