Modified models of radiation pressure instability in application to 10, 10$^5$, and 10$^7$ $M_{\odot}$ accreting black holes

TL;DR

This study models radiation pressure instability in accretion disks around black holes of various masses, revealing how magnetic fields and disk size influence variability patterns, and explaining phenomena like heartbeat states and TDE-related variability.

Contribution

It introduces a modified, time-dependent accretion disk model that incorporates magnetic fields, disk corona coupling, and the effects of TDEs to explain diverse black hole variability phenomena.

Findings

Disk outburst behavior depends on magnetic field strength and outer radius.

Microquasar variability periods decrease with magnetic field strength.

Large black hole masses show non-monotonic period dependence on magnetic fields.

Abstract

Some of the accreting black holes exhibit much stronger variability patterns than the usual stochastic variations. Radiation pressure instability is one of the proposed mechanisms which could account for this effect. We aim to model luminosity changes for objects with black hole mass of 10, 10$^5$, and 10$^7$ solar masses, using the time-dependent evolution of an accretion disk unstable due to the dominant radiation pressure. We use a 1-dimensional, vertically integrated time-dependent numerical scheme which models simultaneous evolution of the disk and corona, coupled by the vertical mass exchange. We also discuss the possibility of presence of an inner optically thin flow, namely the Advection-Dominated Accretion Flow (ADAF). We found that the outburst character strongly depends on the magnetic field and the outer radius of the disk if this radius is smaller (due to TDE phenomenon) than the size of the instability zone in a stationary disk with infinite radius. For microquasars, the dependence on the magnetic field is monotonic, and the period decreases with the field strength. For larger black hole masses, the dependence is non-monotonic, and initial rise of the period is later replaced with the relatively rapid decrease as the magnetic field continues to rise. Still stronger magnetic field stabilizes the disk. Our computations confirm that the radiation pressure instability model can account for heartbeat states in microquasars. Rapid variability detected in IMBH in the form of Quasi-Periodic Ejection can be consistent with the model but only if combined with TDE phenomenon. Yearly repeating variability in Changing Look AGN also requires, in our model, small outer radius either due to the recent TDE or due to the presence of the gap in the disk related to the presence of a secondary black hole.