The Decoupling of Binaries from Their Circumbinary Disks
We have investigated, both analytically and numerically, accreting supermassive black hole binaries as they inspiral due to gravitational radiation to elucidate the decoupling of binaries from their disks and inform future multimessenger observations of these systems. Our numerical studies evolve eq...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/acd183 |
| _version_ | 1797694834162532352 |
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| author | Alexander J. Dittmann Geoffrey Ryan M. Coleman Miller |
| author_facet | Alexander J. Dittmann Geoffrey Ryan M. Coleman Miller |
| author_sort | Alexander J. Dittmann |
| collection | DOAJ |
| description | We have investigated, both analytically and numerically, accreting supermassive black hole binaries as they inspiral due to gravitational radiation to elucidate the decoupling of binaries from their disks and inform future multimessenger observations of these systems. Our numerical studies evolve equal-mass binaries from initial separations of 100 GM c ^−2 until merger, resolving scales as small as ∼0.04 GM c ^−2 , where M is the total binary mass. Our simulations accurately capture the point at which the orbital evolution of each binary decouples from that of its circumbinary disk, and precisely resolve the flow of gas throughout the inspiral. We demonstrate analytically and numerically that timescale-based predictions overestimate the binary separations at which decoupling occurs by factors of ∼3, and illustrate the utility of a velocity-based decoupling criterion. High-viscosity ( ν ≳ 0.03 GM c ^−2 ) circumbinary systems decouple late ( a _b ≲ 15 GM c ^−2 ) and have qualitatively similar morphologies near merger to circumbinary systems with constant binary separations. Lower-viscosity circumbinary disks decouple earlier and exhibit qualitatively different accretion flows, which lead to precipitously decreasing accretion onto the binary. If detected, such a decrease may unambiguously identify the host galaxy of an ongoing event within a LISA error volume. We illustrate how accretion amplitude and variability evolve as binaries gradually decouple from their circumbinary disks, and where decoupling occurs over the course of binary inspirals in the LISA band. We show that, even when dynamically negligible, gas may leave a detectable imprint on the phase of gravitational waves. |
| first_indexed | 2024-03-12T03:02:32Z |
| format | Article |
| id | doaj.art-dac2405dfec645b88321f11140e6cfcf |
| institution | Directory Open Access Journal |
| issn | 2041-8205 |
| language | English |
| last_indexed | 2024-03-12T03:02:32Z |
| publishDate | 2023-01-01 |
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| series | The Astrophysical Journal Letters |
| spelling | doaj.art-dac2405dfec645b88321f11140e6cfcf2023-09-03T14:37:48ZengIOP PublishingThe Astrophysical Journal Letters2041-82052023-01-019492L3010.3847/2041-8213/acd183The Decoupling of Binaries from Their Circumbinary DisksAlexander J. Dittmann0https://orcid.org/0000-0001-6157-6722Geoffrey Ryan1https://orcid.org/0000-0001-9068-7157M. Coleman Miller2https://orcid.org/0000-0002-2666-728XDepartment of Astronomy and Joint Space-Science Institute, University of Maryland , College Park, MD 20742-2421, USA ; dittmann@astro.umd.eduPerimeter Institute for Theoretical Physics , 31 Caroline St.N., Waterloo, ON, N2L 2Y5, CanadaDepartment of Astronomy and Joint Space-Science Institute, University of Maryland , College Park, MD 20742-2421, USA ; dittmann@astro.umd.eduWe have investigated, both analytically and numerically, accreting supermassive black hole binaries as they inspiral due to gravitational radiation to elucidate the decoupling of binaries from their disks and inform future multimessenger observations of these systems. Our numerical studies evolve equal-mass binaries from initial separations of 100 GM c ^−2 until merger, resolving scales as small as ∼0.04 GM c ^−2 , where M is the total binary mass. Our simulations accurately capture the point at which the orbital evolution of each binary decouples from that of its circumbinary disk, and precisely resolve the flow of gas throughout the inspiral. We demonstrate analytically and numerically that timescale-based predictions overestimate the binary separations at which decoupling occurs by factors of ∼3, and illustrate the utility of a velocity-based decoupling criterion. High-viscosity ( ν ≳ 0.03 GM c ^−2 ) circumbinary systems decouple late ( a _b ≲ 15 GM c ^−2 ) and have qualitatively similar morphologies near merger to circumbinary systems with constant binary separations. Lower-viscosity circumbinary disks decouple earlier and exhibit qualitatively different accretion flows, which lead to precipitously decreasing accretion onto the binary. If detected, such a decrease may unambiguously identify the host galaxy of an ongoing event within a LISA error volume. We illustrate how accretion amplitude and variability evolve as binaries gradually decouple from their circumbinary disks, and where decoupling occurs over the course of binary inspirals in the LISA band. We show that, even when dynamically negligible, gas may leave a detectable imprint on the phase of gravitational waves.https://doi.org/10.3847/2041-8213/acd183Active galactic nucleiAccretionGravitational wave astronomyHydrodynamical simulations |
| spellingShingle | Alexander J. Dittmann Geoffrey Ryan M. Coleman Miller The Decoupling of Binaries from Their Circumbinary Disks The Astrophysical Journal Letters Active galactic nuclei Accretion Gravitational wave astronomy Hydrodynamical simulations |
| title | The Decoupling of Binaries from Their Circumbinary Disks |
| title_full | The Decoupling of Binaries from Their Circumbinary Disks |
| title_fullStr | The Decoupling of Binaries from Their Circumbinary Disks |
| title_full_unstemmed | The Decoupling of Binaries from Their Circumbinary Disks |
| title_short | The Decoupling of Binaries from Their Circumbinary Disks |
| title_sort | decoupling of binaries from their circumbinary disks |
| topic | Active galactic nuclei Accretion Gravitational wave astronomy Hydrodynamical simulations |
| url | https://doi.org/10.3847/2041-8213/acd183 |
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