Observability of Isolated Stellar-mass Black Holes

Stellar-mass black holes (BHs) represent the natural end states of massive stars. It is estimated that 10 ^8 stellar-mass BHs are present in the Milky Way galaxy, a significant fraction of which are expected to be isolated. Despite their expected abundance, only about 20 have been detected so far—mo...

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Main Authors: Lena Murchikova, Kailash C. Sahu
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal Letters
Subjects:
Online Access:https://doi.org/10.3847/2041-8213/ade7f8
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author Lena Murchikova
Kailash C. Sahu
author_facet Lena Murchikova
Kailash C. Sahu
author_sort Lena Murchikova
collection DOAJ
description Stellar-mass black holes (BHs) represent the natural end states of massive stars. It is estimated that 10 ^8 stellar-mass BHs are present in the Milky Way galaxy, a significant fraction of which are expected to be isolated. Despite their expected abundance, only about 20 have been detected so far—mostly in binary systems—with just one confirmed isolated black hole (IsoBH) identified via astrometric microlensing. In this study, we investigate the potential for detecting electromagnetic emissions from IsoBHs by generating synthetic model spectra of their emissions in different types of interstellar medium environments. These model spectra are then compared with current observational capabilities. We show that photons emitted by IsoBHs—especially those accreting material in dense environments or within the solar neighborhood—should be readily detectable. However, confidently identifying these sources remains highly challenging. We conclude that a number of IsoBHs must already exist in current astronomical catalogs but have not been identified as such. We outline possible strategies for the detection and identification of IsoBHs using the current and upcoming telescopes.
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spelling doaj-art-9182dfefdf9b46509b09be52f6f8baae2025-08-20T03:27:57ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019881L1210.3847/2041-8213/ade7f8Observability of Isolated Stellar-mass Black HolesLena Murchikova0https://orcid.org/0000-0001-8986-5403Kailash C. Sahu1https://orcid.org/0000-0001-6008-1955Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University , Evanston, IL 60208, USA ; lena@northwestern.edu; Department of Physics & Astronomy, Northwestern University , Evanston, IL 60208, USA; School of Natural Sciences, Institute for Advanced Study , 1 Einstein Drive, Princeton, NJ 08540, USASpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA ; ksahu@stsci.edu; Eureka Scientific Inc. , 2542 Delmar Avenue, Suite 100, Oakland, CA 94602-3017, USAStellar-mass black holes (BHs) represent the natural end states of massive stars. It is estimated that 10 ^8 stellar-mass BHs are present in the Milky Way galaxy, a significant fraction of which are expected to be isolated. Despite their expected abundance, only about 20 have been detected so far—mostly in binary systems—with just one confirmed isolated black hole (IsoBH) identified via astrometric microlensing. In this study, we investigate the potential for detecting electromagnetic emissions from IsoBHs by generating synthetic model spectra of their emissions in different types of interstellar medium environments. These model spectra are then compared with current observational capabilities. We show that photons emitted by IsoBHs—especially those accreting material in dense environments or within the solar neighborhood—should be readily detectable. However, confidently identifying these sources remains highly challenging. We conclude that a number of IsoBHs must already exist in current astronomical catalogs but have not been identified as such. We outline possible strategies for the detection and identification of IsoBHs using the current and upcoming telescopes.https://doi.org/10.3847/2041-8213/ade7f8Astrophysical black holesBlack holesStellar mass black holesAccretionInterstellar medium
spellingShingle Lena Murchikova
Kailash C. Sahu
Observability of Isolated Stellar-mass Black Holes
The Astrophysical Journal Letters
Astrophysical black holes
Black holes
Stellar mass black holes
Accretion
Interstellar medium
title Observability of Isolated Stellar-mass Black Holes
title_full Observability of Isolated Stellar-mass Black Holes
title_fullStr Observability of Isolated Stellar-mass Black Holes
title_full_unstemmed Observability of Isolated Stellar-mass Black Holes
title_short Observability of Isolated Stellar-mass Black Holes
title_sort observability of isolated stellar mass black holes
topic Astrophysical black holes
Black holes
Stellar mass black holes
Accretion
Interstellar medium
url https://doi.org/10.3847/2041-8213/ade7f8
work_keys_str_mv AT lenamurchikova observabilityofisolatedstellarmassblackholes
AT kailashcsahu observabilityofisolatedstellarmassblackholes