A disk instability model for the quasi-periodic eruptions of GSN 069

TL;DR

This paper develops a disk instability model incorporating viscous torque effects to explain the quasi-periodic eruptions of GSN 069, successfully reproducing observed X-ray light curves and spectra.

Contribution

It improves previous models by including a non-zero viscous torque condition and a general viscous stress form in Kerr metric, explaining GSN 069's QPEs.

Findings

Model qualitatively reproduces GSN 069's X-ray light curves and spectra.

Parameter fects light curve profiles, indicating broader applicability.

Model may be applicable to other QPE sources.

Abstract

GSN 069 is a recently discovered QPE (Quasi-periodic eruptions) source recurring about every 9 hours. The mechanism for the QPEs of GSN 069 is still unclear so far. In this work, a disk instability model is constructed to explain GSN 069 based on Pan et al. (2021) (PLC21), where the authors proposed a toy model for the repeating changing-look (CL) active galactic nuclei (AGN). We improve the work of PLC21 by including a non-zero viscous torque condition on the inner boundary of disk and adopting a general form for the viscous stress torque in Kerr metric. It is found that the 0.4-2 keV light curves, the light curves at different energy bands and the phase-resolved X-ray spectrum of GSN 069 can all be qualitatively reproduced by our model. Furthermore, the profiles of light curve in QPEs can be significantly changed by the parameter \mu in viscous torque equation, which implies that our model may also be applied to other QPEs.