Magnetized Accretion Disks with Outflows for Changing-look AGNs

TL;DR

This paper investigates how magnetic pressure-dominated accretion disks with outflows can explain the rapid variability observed in changing-look active galactic nuclei, challenging standard accretion models.

Contribution

It introduces a model of magnetic pressure-dominated disks with outflows that shortens accretion timescales, explaining CL-AGN variability beyond standard theories.

Findings

Magnetic pressure-dominated disks have shorter accretion timescales than standard thin disks.

Outflows further reduce the accretion timescale, aligning with CL-AGN observations.

The proposed model explains rapid variability in CL-AGNs effectively.

Abstract

Changing-look active galactic nuclei (CL-AGNs) challenges the standard accretion theory owing to its rapid variability. Recent numerical simulations have shown that, for the sub-Eddington accretion case, the disk is magnetic pressure-dominated, thermally stable, and geometrically thicker than the standard disk. In addition, outflows were found in the simulations. Observationally, high blueshifted velocities absorption lines indicate that outflows exist in AGNs. In this work, based on the simulation results, we investigate the magnetic pressure-dominated disk, and find that the accretion timescale is significantly shorter than that of the standard thin disk. However, such a timescale is still longer than that of the CL-AGNs. Moreover, if the role of outflows is taken into account, then the accretion timescale can be even shortened. By the detailed comparison of the theoretical accretion timescale with the observations, we propose that the magnetic pressure-dominated disk incorporating outflows can be responsible for the rapid variability of CL-AGNs.