| Issue |
A&A
Volume 695, March 2025
|
|
|---|---|---|
| Article Number | L19 | |
| Number of page(s) | 5 | |
| Section | Letters to the Editor | |
| DOI | https://doi.org/10.1051/0004-6361/202453324 | |
| Published online | 21 March 2025 | |
Letter to the Editor
The star grinder in the Galactic centre
Uncovering the highly compact central stellar-mass black hole cluster
1
Charles University, Faculty of Mathematics and Physics, Astronomical Institute, V Holešovičkách 2, CZ-18000 Prague, Czech Republic
2
Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, Nussallee 14-16, D-53115 Bonn, Germany
⋆ Corresponding author; haas@sirrah.troja.mff.cuni.cz
Received:
6
December
2024
Accepted:
26
February
2025
Context. Various past theoretical considerations and observational efforts suggest the presence of a population of stellar-mass black holes in the innermost parsec of the Galactic centre.
Aims. In this Letter, we investigate the impact of these black holes on the composition of the embedding stellar population through their direct collisions with the individual stars. Based on the estimated collision rates, we derive an order of magnitude radial density profile of the black hole cluster.
Methods. The estimates were obtained analytically, considering various possible formation channels for the black holes and the observed present-day properties of the stellar populations in the Galactic centre.
Results. We find that the collisions of the stars and the black holes can lead to the depletion of the most massive stars within the S-cluster on a timescale of a few million years. The necessary black hole cluster density is compatible with the recurrent in situ star formation in the innermost parsec of the Galactic centre. We suggest that such a depletion naturally explains the reported lack of stars of the stellar type O and of the Galactic halo hyper-velocity star counterparts within the S-cluster.
Key words: stars: black holes / stars: kinematics and dynamics / Galaxy: center
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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