Galactic Isolated Stellar-mass Black Holes with the Magnetospheric Spark Gap as Possible GeV–TeV Gamma-Ray Unidentified Sources

Billions of isolated stellar-mass black holes (IBHs) are thought to wander through the interstellar medium (ISM) in the Galaxy, yet only one has been detected. IBHs embedded in ISM would accrete gas via Bondi–Hoyle–Littleton accretion, and with efficient magnetic flux accumulation, the magnetosphere...

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Main Authors: Koki Kin, Riku Kuze, Shigeo S. Kimura
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
Subjects:
Online Access:https://doi.org/10.3847/1538-4357/adcb3d
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author Koki Kin
Riku Kuze
Shigeo S. Kimura
author_facet Koki Kin
Riku Kuze
Shigeo S. Kimura
author_sort Koki Kin
collection DOAJ
description Billions of isolated stellar-mass black holes (IBHs) are thought to wander through the interstellar medium (ISM) in the Galaxy, yet only one has been detected. IBHs embedded in ISM would accrete gas via Bondi–Hoyle–Littleton accretion, and with efficient magnetic flux accumulation, the magnetosphere would be formed in the vicinity of IBHs. We explore the detectability of such IBHs through high-energy gamma-rays from spark gaps in their magnetospheres based on our recent numerical simulation. Spark gap gamma-rays can be bright at the GeV–TeV energies when IBHs are in the dense ISM. About 10 ^3 and 10 IBHs might be contained in unidentified objects of the Fermi Large Area Telescope and the High Energy Stereoscopic System, respectively. A future Galactic plane survey by the Cherenkov Telescope Array Observatory would lead to ∼10 ^2 detections. We also evaluate the combined gamma-ray emission of IBHs in the Galaxy and find that the IBHs may contribute to the Galactic diffuse gamma-rays. IBHs will emit optical and X-ray photons from their accretion disk as counterparts, potentially useful for identifying candidates.
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spelling doaj-art-0a35e9ca5dbf4b96b5c6783afc26a6062025-08-20T02:17:01ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01985225110.3847/1538-4357/adcb3dGalactic Isolated Stellar-mass Black Holes with the Magnetospheric Spark Gap as Possible GeV–TeV Gamma-Ray Unidentified SourcesKoki Kin0https://orcid.org/0000-0002-9712-3589Riku Kuze1https://orcid.org/0000-0002-5916-788XShigeo S. Kimura2https://orcid.org/0000-0003-2579-7266Astronomical Institute, Graduate School of Science, Tohoku University , Sendai 980-8578, JapanAstronomical Institute, Graduate School of Science, Tohoku University , Sendai 980-8578, Japan; Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto University , Kyoto 606-8502, JapanAstronomical Institute, Graduate School of Science, Tohoku University , Sendai 980-8578, Japan; Frontier Research Institute for Interdisciplinary Sciences, Tohoku University , Sendai 980-8578, JapanBillions of isolated stellar-mass black holes (IBHs) are thought to wander through the interstellar medium (ISM) in the Galaxy, yet only one has been detected. IBHs embedded in ISM would accrete gas via Bondi–Hoyle–Littleton accretion, and with efficient magnetic flux accumulation, the magnetosphere would be formed in the vicinity of IBHs. We explore the detectability of such IBHs through high-energy gamma-rays from spark gaps in their magnetospheres based on our recent numerical simulation. Spark gap gamma-rays can be bright at the GeV–TeV energies when IBHs are in the dense ISM. About 10 ^3 and 10 IBHs might be contained in unidentified objects of the Fermi Large Area Telescope and the High Energy Stereoscopic System, respectively. A future Galactic plane survey by the Cherenkov Telescope Array Observatory would lead to ∼10 ^2 detections. We also evaluate the combined gamma-ray emission of IBHs in the Galaxy and find that the IBHs may contribute to the Galactic diffuse gamma-rays. IBHs will emit optical and X-ray photons from their accretion disk as counterparts, potentially useful for identifying candidates.https://doi.org/10.3847/1538-4357/adcb3dBlack holesAccretionGamma-ray sourcesPlasma astrophysics
spellingShingle Koki Kin
Riku Kuze
Shigeo S. Kimura
Galactic Isolated Stellar-mass Black Holes with the Magnetospheric Spark Gap as Possible GeV–TeV Gamma-Ray Unidentified Sources
The Astrophysical Journal
Black holes
Accretion
Gamma-ray sources
Plasma astrophysics
title Galactic Isolated Stellar-mass Black Holes with the Magnetospheric Spark Gap as Possible GeV–TeV Gamma-Ray Unidentified Sources
title_full Galactic Isolated Stellar-mass Black Holes with the Magnetospheric Spark Gap as Possible GeV–TeV Gamma-Ray Unidentified Sources
title_fullStr Galactic Isolated Stellar-mass Black Holes with the Magnetospheric Spark Gap as Possible GeV–TeV Gamma-Ray Unidentified Sources
title_full_unstemmed Galactic Isolated Stellar-mass Black Holes with the Magnetospheric Spark Gap as Possible GeV–TeV Gamma-Ray Unidentified Sources
title_short Galactic Isolated Stellar-mass Black Holes with the Magnetospheric Spark Gap as Possible GeV–TeV Gamma-Ray Unidentified Sources
title_sort galactic isolated stellar mass black holes with the magnetospheric spark gap as possible gev tev gamma ray unidentified sources
topic Black holes
Accretion
Gamma-ray sources
Plasma astrophysics
url https://doi.org/10.3847/1538-4357/adcb3d
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