Modified models of radiation pressure instability applied to 10, 10⁵, and 10⁷ M_⊙ accreting black holes

Abstract

Context. Some accreting black holes exhibit much stronger variability patterns than the usual stochastic variations. Radiation pressure instability is one of the proposed mechanisms that might account for this effect. Aims. We model luminosity changes for objects with a black hole mass of 10, 105, and 107 solar masses, using the time-dependent evolution of an accretion disk that is unstable as a result of the dominant radiation pressure. We concentrate on the outburst timescales. We explore the influence of the hot coronal flow above the cold disk, the inner purely hot flow, and the effect of the magnetic field on the time evolution of the disk-corona system. For intermediate-mass black holes and active galactic nuclei, we also explore the role of the disk outer radius because a disk that is fed by tidal disruption events (TDE) can be quite small. Methods. We used a 1D vertically integrated time-dependent numerical scheme that models the simultaneous evolution of the disk and corona, which is coupled by the vertical mass exchange. We parameterized the strength of the large-scale toroidal magnetic fields according to a local accretion rate. We also discuss a possible inner optically thin flow, the advection-dominated accretion flow (ADAF). This flow would require modification of the inner boundary condition of the cold disk flow. For the set of the global parameters, we calculated the variability timescales and outburst amplitudes of the disk and the corona. Results. We found that the role of the inner ADAF and the accreting corona are relatively unimportant, but the outburst character strongly depends on the magnetic field and on the outer radius of the disk if this radius is smaller (due to the 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 higher black hole masses, the dependence is nonmonotonic, and an initial rise of the period is later replaced with a relatively rapid decrease as the magnetic field continues to rise. A still stronger magnetic field stabilizes the disk. When we assumed a smaller disk outer radiusfor 105 and 107 M⊙, the outbursts were shorter and led to complex multiscale outbursts for some parameters, thus approaching the behavior of deterministic chaos. Conclusions. Our computations confirm that the radiation pressure instability model can account for heartbeat states in microquasars. The rapid variability detected in intermediate-mass black holes in the form of quasi-periodic eruptions can be consistent with the model, but only when it is combined with the TDE phenomenon. The yearly repeating variability in changing-look active galactic nuclei in our model also requires a small outer radius either due to the recent TDE or due to the gap in the disk that is related to a secondary black hole.

Dissonance in Harmony: The UV/Optical Periodic Outbursts of ASASSN-14ko Exhibit Repeated Bumps and Rebrightenings

“…This temperature fluctuation bears resemblance to the disk instability scenario. Particularly, we noticed that the disk instability model has been proposed to explain QPEs in previous studies (Pan et al 2023;Śniegowska et al 2023) and the X-ray flares observed in ASASSN-14ko are rather similar to QPEs. Another popular model involved in explaining QPE is the star-disk collision model (Xian et al 2021;Linial & Metzger 2023), which is yet disfavored by a lower energy released by 1 order of magnitude than that observed in individual flares of ASASSN-14ko (∼10 50 erg).…”

EMRI + TDE = QPE: Periodic X-Ray Flares from Star–Disk Collisions in Galactic Nuclei

“…Several theoretical models have been proposed to explain the QPE phenomenon, including (i) accretion disk instabilities (Raj & Nixon 2021;Kaur et al 2023;Pan et al 2022;Sniegowska et al 2023); (ii) gravitational lensing of an SMBH binary (Ingram et al 2021); (iii) mass transfer onto an SMBH from one or more orbiting bodies (Zalamea et al 2010;King 2020;Chen et al 2023;King 2022King , 2023Krolik & Linial 2022;Linial & Sari 2023;Lu & Quataert 2023;Metzger et al 2022;Wang et al 2022;Zhao et al 2022);and (iv) collisions between an orbiting secondary body and the SMBH accretion disk (Suková et al 2021;Xian et al 2021;Franchini et al 2023). We focus on the latter scenario here.…”

Application of the Disk Instability Model to All Quasiperiodic Eruptions

“…The primary challenges of this phenomenon are how to construct a physical scenario to produce such short periodic eruptions (several to a dozen of hours). A number of models have been proposed, which can be roughly divided into two categories: while the first one suggests that the periodic outbursts in QPEs originate from the periodic orbital motion of a star captured by a black hole (King 2020(King , 2022Ingram et al 2021;Suková et al 2021;Xian et al 2021;Chen et al 2023;Krolik & Linial 2022;Lu & Quataert 2022;Linial & Sari 2023;Metzger et al 2022;Wang et al 2022b;Franchini et al 2023;Linial & Metzger 2023;Tagawa & Haiman 2023), another one ascribes the periodic behavior to the instability of inner accretion disk dominated by radiation pressure (Sniegowska et al 2020;Pan et al 2021Pan et al , 2022Raj & Nixon 2021;Kaur et al 2023;Śniegowska 2023). Notably, only the model of Pan et al (2022) is able to fit both the light curves and the phase-resolved X-ray spectra simultaneously during outbursts in GSN 069.…”

“…The main difficulty of this disk instability model for QPEs is the viscous timescale of the thin accretion disk being significantly larger than the observed periods of QPEs (e.g., Pan et al 2021Pan et al , 2022. It was suggested that the viscous timescale of a disk driven predominantly by magnetic outflows can be substantially shortened (Cao & Spruit 2013;Li & Begelman 2014;Li & Cao 2019;Feng & Cao 2021;Kaur et al 2023;Pan et al 2022;Śniegowska 2023). Pan et al (2022) constructed an instability model of the disk with magnetically driven outflows for the QPEs of GSN 069, and both its light curve and phased-resolved X-ray spectra have been fitted by their model fairly well.…”