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