Radiation Magnetohydrodynamic Simulation of Sub-Eddington Circumbinary Disk around an Equal-mass Massive Black Hole Binary

We present the first three-dimensional radiation magnetohydrodynamic (RMHD) simulation of a sub-Eddington circumbinary disk (CBD) around an equal-mass massive black hole binary with a total mass of 2 × 10 ^7 M _⊙ on a circular orbit, separated by 100 GM _tot / c ^2 . The inclusion of radiation leads...

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Main Authors: Vishal Tiwari, Chi-Ho Chan, Tamara Bogdanović, Yan-Fei Jiang, Shane W. Davis, Simon Ferrel
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/add408
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author Vishal Tiwari
Chi-Ho Chan
Tamara Bogdanović
Yan-Fei Jiang
Shane W. Davis
Simon Ferrel
author_facet Vishal Tiwari
Chi-Ho Chan
Tamara Bogdanović
Yan-Fei Jiang
Shane W. Davis
Simon Ferrel
author_sort Vishal Tiwari
collection DOAJ
description We present the first three-dimensional radiation magnetohydrodynamic (RMHD) simulation of a sub-Eddington circumbinary disk (CBD) around an equal-mass massive black hole binary with a total mass of 2 × 10 ^7 M _⊙ on a circular orbit, separated by 100 GM _tot / c ^2 . The inclusion of radiation leads to a denser, thinner, and more filamentary disk compared to nonradiative magnetohydrodynamic simulation, primarily due to reduced pressure support and an altered equation of state. The RMHD disk also features ∼3 times lower accretion rate ( $\approx 0.15\,{\dot{M}}_{{\rm{Edd}}}$ ), weaker accretion streams, and a less pronounced overdensity (a.k.a., “lump”) at the inner edge. Our analysis of the light curves and thermal spectra reveals that the variability induced by the binary–CBD interaction is distinguishable in the optical/UV band, where CBD shines at about 1% of the Eddington luminosity. These findings underscore the crucial role of radiation on the structure and observational properties of CBDs around massive black hole binaries and have implications for detecting electromagnetic counterparts to Laser Interferometer Space Antenna gravitational-wave precursors, and for heavier binaries that are Pulsar Timing Array sources.
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spelling doaj-art-59ec753575c14cd4a1f4e842018aa4c22025-08-20T03:16:11ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01986215810.3847/1538-4357/add408Radiation Magnetohydrodynamic Simulation of Sub-Eddington Circumbinary Disk around an Equal-mass Massive Black Hole BinaryVishal Tiwari0https://orcid.org/0000-0002-7110-9885Chi-Ho Chan1https://orcid.org/0000-0001-5949-6109Tamara Bogdanović2https://orcid.org/0000-0002-7835-7814Yan-Fei Jiang3https://orcid.org/0000-0002-2624-3399Shane W. Davis4https://orcid.org/0000-0001-7488-4468Simon Ferrel5Center for Relativistic Astrophysics and School of Physics , Georgia Institute of Technology, Atlanta, GA 30332, USA ; vtiwari@gatech.eduCenter for Relativistic Astrophysics and School of Physics , Georgia Institute of Technology, Atlanta, GA 30332, USA ; vtiwari@gatech.eduCenter for Relativistic Astrophysics and School of Physics , Georgia Institute of Technology, Atlanta, GA 30332, USA ; vtiwari@gatech.eduCenter for Computational Astrophysics , Flatiron Institute, 162 Fifth Avenue, New York, NY 10010, USADepartment of Astronomy, University of Virginia , Charlottesville, VA 22904, USACenter for Relativistic Astrophysics and School of Physics , Georgia Institute of Technology, Atlanta, GA 30332, USA ; vtiwari@gatech.eduWe present the first three-dimensional radiation magnetohydrodynamic (RMHD) simulation of a sub-Eddington circumbinary disk (CBD) around an equal-mass massive black hole binary with a total mass of 2 × 10 ^7 M _⊙ on a circular orbit, separated by 100 GM _tot / c ^2 . The inclusion of radiation leads to a denser, thinner, and more filamentary disk compared to nonradiative magnetohydrodynamic simulation, primarily due to reduced pressure support and an altered equation of state. The RMHD disk also features ∼3 times lower accretion rate ( $\approx 0.15\,{\dot{M}}_{{\rm{Edd}}}$ ), weaker accretion streams, and a less pronounced overdensity (a.k.a., “lump”) at the inner edge. Our analysis of the light curves and thermal spectra reveals that the variability induced by the binary–CBD interaction is distinguishable in the optical/UV band, where CBD shines at about 1% of the Eddington luminosity. These findings underscore the crucial role of radiation on the structure and observational properties of CBDs around massive black hole binaries and have implications for detecting electromagnetic counterparts to Laser Interferometer Space Antenna gravitational-wave precursors, and for heavier binaries that are Pulsar Timing Array sources.https://doi.org/10.3847/1538-4357/add408Radiative magnetohydrodynamicsSupermassive black holesGravitational wave sourcesAccretionBlack hole physicsGravitation
spellingShingle Vishal Tiwari
Chi-Ho Chan
Tamara Bogdanović
Yan-Fei Jiang
Shane W. Davis
Simon Ferrel
Radiation Magnetohydrodynamic Simulation of Sub-Eddington Circumbinary Disk around an Equal-mass Massive Black Hole Binary
The Astrophysical Journal
Radiative magnetohydrodynamics
Supermassive black holes
Gravitational wave sources
Accretion
Black hole physics
Gravitation
title Radiation Magnetohydrodynamic Simulation of Sub-Eddington Circumbinary Disk around an Equal-mass Massive Black Hole Binary
title_full Radiation Magnetohydrodynamic Simulation of Sub-Eddington Circumbinary Disk around an Equal-mass Massive Black Hole Binary
title_fullStr Radiation Magnetohydrodynamic Simulation of Sub-Eddington Circumbinary Disk around an Equal-mass Massive Black Hole Binary
title_full_unstemmed Radiation Magnetohydrodynamic Simulation of Sub-Eddington Circumbinary Disk around an Equal-mass Massive Black Hole Binary
title_short Radiation Magnetohydrodynamic Simulation of Sub-Eddington Circumbinary Disk around an Equal-mass Massive Black Hole Binary
title_sort radiation magnetohydrodynamic simulation of sub eddington circumbinary disk around an equal mass massive black hole binary
topic Radiative magnetohydrodynamics
Supermassive black holes
Gravitational wave sources
Accretion
Black hole physics
Gravitation
url https://doi.org/10.3847/1538-4357/add408
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