Multi-wavelength Emission Modeling from Accretion Flows around Isolated Black Holes Including Magnetic Flux Transport
Abstract
Isolated stellar-mass black holes (IBHs) are expected to be abundant in the Milky Way, yet their electromagnetic signatures remain largely undetected. We investigate the detectability of IBHs in molecular clouds using a 1D, multi-wavelength emission model that incorporates magnetic flux transport controlled by the magnetic Prandtl number Pm. We find that magnetically arrested disks (MADs) form for Pm≳ 1, where the magnetic flux threading the black hole is in a saturation value. On the other hand, MAD formation is restricted to a limited parameter range for Pm<1, In our model, outer parts of accretion disks, around 100 gravitational radii, efficiently emit infrared photons detectable by WISE. This feature is not captured by the conventional one-zone model. X-ray emission depends strongly on Pm; For Pm=1 where MAD is formed, X-ray emission is dominated by nonthermal radiation, whereas inverse Compton emission becomes dominant for Pm=0.5 where the magnetic field is weaker than the saturation value. X-ray detection is plausible if they are in dense molecular-cloud filaments for Pm≥1, although it is challenging for Pm< 1. These results demonstrate that magnetic flux transport plays a key role in shaping the multiwavelength observational signatures of IBHs.
Versions
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BibTeX
@misc{koshimizu2026multiwavelength,
title = {{Multi-wavelength Emission Modeling from Accretion Flows around Isolated Black Holes Including Magnetic Flux Transport}},
author = {Takumi Koshimizu and Shigeo S. Kimura},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.31477},
eprint = {2606.31477},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.31477},
}
RIS
TY - UNPB
TI - Multi-wavelength Emission Modeling from Accretion Flows around Isolated Black Holes Including Magnetic Flux Transport
AU - Takumi Koshimizu
AU - Shigeo S. Kimura
PY - 2026
DA - 2026/09/19
PB - arXiv
DO - 10.48550/arxiv.2606.31477
UR - https://arxiv.org/abs/2606.31477
AB - Isolated stellar-mass black holes (IBHs) are expected to be abundant in the Milky Way, yet their electromagnetic signatures remain largely undetected. We investigate the detectability of IBHs in molecular clouds using a 1D, multi-wavelength emission model that incorporates magnetic flux transport controlled by the magnetic Prandtl number P_m. We find that magnetically arrested disks (MADs) form for P_m≳ 1, where the magnetic flux threading the black hole is in a saturation value. On the other hand, MAD formation is restricted to a limited parameter range for P_m<1, In our model, outer parts of accretion disks, around 100 gravitational radii, efficiently emit infrared photons detectable by WISE. This feature is not captured by the conventional one-zone model. X-ray emission depends strongly on P_m; For P_m=1 where MAD is formed, X-ray emission is dominated by nonthermal radiation, whereas inverse Compton emission becomes dominant for P_m=0.5 where the magnetic field is weaker than the saturation value. X-ray detection is plausible if they are in dense molecular-cloud filaments for P_m≥1, although it is challenging for P_m< 1. These results demonstrate that magnetic flux transport plays a key role in shaping the multiwavelength observational signatures of IBHs.
ER -