Abstract
In many black hole (BH) systems, the accretion disk is expected to be misaligned with respect to the BH spin axis. If the scale height of the disk is much smaller than the misalignment angle, the spin of the BH can tear the disk into multiple, independently precessing “sub-disks.” This is most likely to happen during outbursts in black hole X-Ray binaries (BHXRBs) and in active galactic nuclei (AGNs) accreting above a few percent of the Eddington limit, because the disk becomes razor-thin. Disk tearing has the potential to explain variability phenomena including quasi-periodic oscillations in BHXRBs and changing-look phenomena in AGNs. Here, we present the first radiative two-temperature general relativistic magnetohydrodynamic (GRMHD) simulation of a strongly tilted (65°) accretion disk around an M BH = 10 M ⊙ BH, which tears and precesses. This leads to luminosity swings between a few percent and 50% of the Eddington limit on sub-viscous timescales. Surprisingly, even where the disk is radiation-pressure-dominated, the accretion disk is thermally stable over t ≳ 14,000 r g /c. This suggests warps play an important role in stabilizing the disk against thermal collapse. The disk forms two nozzle shocks perpendicular to the line of nodes where the scale height of the disk decreases tenfold and the electron temperature reaches T e ∼ 108-109 K. In addition, optically thin gas crossing the tear between the inner and outer disk gets heated to T e ∼ 108 K. This suggests that warped disks may emit a Comptonized spectrum that deviates substantially from idealized models.
| Original language | English (US) |
|---|---|
| Article number | L48 |
| Journal | Astrophysical Journal Letters |
| Volume | 944 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 1 2023 |
Funding
We thank Michiel van der Klis, Adam Ingram, Sera Markoff, and Ramesh Narayan for insightful discussions. An award of computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE), OLCF Director\u2019s Discretionary Allocation, and ASCR Leadership Computing Challenge (ALCC) programs under award PHY129. This research used resources of the Oak Ridge Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC05-00OR22725. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 using NERSC award ALCC-ERCAP0022634. We acknowledge PRACE for awarding us access to JUWELS Booster at GCS@JSC, Germany. M.L. was supported by the John Harvard Distinguished Science Fellowship, G.M. is supported by a Netherlands Research School for Astronomy (NOVA), Virtual Institute of Accretion (VIA) postdoctoral fellowship, N.K. by an NSF Graduate Research Fellowship, and A.T. by the National Science Foundation grants AST-2206471, AST-2009884,AST-2107839, AST-1815304, OAC-2031997, and AST-1911080.
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science