Super-Eddington accretion onto black holes and its application to fallback accretion
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| Format: | Preprint |
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2025
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| _version_ | 1866916858251182080 |
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| author | Faran, Tamar Quataert, Eliot |
| author_facet | Faran, Tamar Quataert, Eliot |
| contents | We study the problem of steady-state spherical accretion onto a black hole, in which the internal energy of the flow is governed by radiation and photon diffusion dominates the energy flux at large radii. In the free-fall limit, the fluid equations can admit two types of solutions for a given accretion rate: (1) accretion flows that become isothermal at large radii and (2) solutions in which the temperature at infinity vanishes as a power law of the radius. Using boundary layer theory, we obtain analytic solutions for the two cases and apply our results to fallback accretion onto a black hole following a failed supernova explosion. We give predictions for the observational signature of fallback accretion using realistic progenitor properties from MESA, both for a fully ionized inflow and for the more realistic case in which recombination/ionization take place due to low photospheric temperatures. The observed fading sources coincident with the failed-supernova candidates in NGC 6946 and M31 are too luminous to be powered by spherical accretion onto newly formed black holes; the observed sources are instead likely due to accretion of the turbulent, convective envelope of the supergiant progenitor. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2507_16893 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Super-Eddington accretion onto black holes and its application to fallback accretion Faran, Tamar Quataert, Eliot High Energy Astrophysical Phenomena We study the problem of steady-state spherical accretion onto a black hole, in which the internal energy of the flow is governed by radiation and photon diffusion dominates the energy flux at large radii. In the free-fall limit, the fluid equations can admit two types of solutions for a given accretion rate: (1) accretion flows that become isothermal at large radii and (2) solutions in which the temperature at infinity vanishes as a power law of the radius. Using boundary layer theory, we obtain analytic solutions for the two cases and apply our results to fallback accretion onto a black hole following a failed supernova explosion. We give predictions for the observational signature of fallback accretion using realistic progenitor properties from MESA, both for a fully ionized inflow and for the more realistic case in which recombination/ionization take place due to low photospheric temperatures. The observed fading sources coincident with the failed-supernova candidates in NGC 6946 and M31 are too luminous to be powered by spherical accretion onto newly formed black holes; the observed sources are instead likely due to accretion of the turbulent, convective envelope of the supergiant progenitor. |
| title | Super-Eddington accretion onto black holes and its application to fallback accretion |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2507.16893 |