Interpreting the Variability of Double-Peaked Emission Lines in Active Galactic Nuclei with Stochastically Perturbed Accretion Disk Models

TL;DR

This paper models the short-term variability of double-peaked emission lines in active galactic nuclei using stochastically perturbed accretion disks, comparing results with observations of specific galaxies to understand the origin of variability.

Contribution

It introduces a stochastic accretion disk model to explain emission line variability and compares it with observed data, providing insights into the physical processes in AGN disks.

Findings

Spots concentrated in outer disk regions reproduce Arp 102B variability.

Models can match 3C 390.3 variability with appropriate parameters.

Outer disk spots suggest self-gravity effects influence emission line variability.

Abstract

In an effort to explain the short-timescale variability of the broad, double-peaked profiles of some active galactic nuclei, we constructed stochastically perturbed accretion disk models and calculated H alpha line profile series as the bright spots rotate, shear and decay. We determined the dependence of the properties of the line profile variability on the spot properties. We compared the variability of the line profile from the models to the observed variability of the H alpha line of Arp 102B and 3C 390.3. We find that spots need to be concentrated in the outer parts of the line emitting region to reproduce the observed variability properties for Arp 102B. This rules out spot production by star/disk collisions and favors a scenario where the radius of marginal self-gravity is within the line emitting region, creating a sharp increase in the radial spot distribution in the outer parts. In the case of 3C 390.3, all the families of models that we tested can reproduce the observed variability for a suitable choice of model parameters.