Decoupling of a supermassive black hole binary from its magnetically arrested circumbinary accretion disk
Abstract
Merging supermassive black hole (SMBH) binaries will likely be surrounded by a circumbinary accretion disk. Close to merger, a gravitational radiation-driven inspiral will happen on timescales faster than the effective viscous time at the disk cavity wall, leading to a decoupling of the inner binary dynamics from the surrounding gaseous environment. Here we perform the first magnetohydrodynamics simulation of this decoupling process from a magnetically arrested circumbinary accretion disk. In this regime, the central cavity is filled with a very strong vertical magnetic flux, regulating accretion onto the binary. Our simulations identify three main stages of this process: (i) large-scale magnetic flux loss prior to decoupling, (ii) Rayleigh-Taylor-driven accretion streams onto the binary during and after decoupling, which can power magnetic towerlike outflows, resembling dual jets, and (iii) postmerger, the cavity wall becomes unstable and the magnetic flux trapped inside the cavity will get ejected in large coherent outbreak episodes with implications for potential multimessenger transients to merging SMBH binaries.
Copyright and License
© 2025 American Physical Society.
Acknowledgement
We thank the anonymous referee for insightful comments and suggestions. The authors are grateful for insightful discussions with Xue-Ning Bai, Luciano Combi, Philip F. Hopkins, Amir Levinson, Douglas N. C. Lin, Sean Ressler, Bart Ripperda, James M. Stone, Alexander Tchekhovskoy, and Jonathan Zrake. The simulations were performed on DOE OLCF Summit under allocation AST198. This research used resources from the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725. Additional simulations were done on DOE NERSC supercomputer Perlmutter under Grant No. m4575. 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 No. NP-ERCAP0028480.
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PhysRevD.111.L081304.pdf
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Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2410.23264v1 (arXiv)
Dates
- Accepted
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2025-04-08Accepted
- Available
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2025-04-22Published online