Stellar Collisions from Self-consistent Stellar Dynamics around Growing Supermassive Black Holes
6 affiliations
- 1Guangzhou University
- 2Key Laboratory for Astronomical Observation and Technology of Guangzhou
- 3Astronomy Science and Technology Research Laboratory of Department of Education of Guangdong Province
- 4Universitat Politècnica de València
- 5Max-Planck-Institute for Extraterrestrial Physics
- 6Kavli Institute for Astronomy and Astrophysics
Abstract
The centers of galaxies harbor the densest stellar environments, where a massive black hole (MBH) accelerates stars to such high velocities that direct collisions can result in high-energetic phenomena, such as gravitational wave sources, kilonovae, and supernova-like transients. These collisions can reshape the cluster’s density profile and release gas that can be subsequently accreted by the MBH. However, the evolving rates of such phenomena from self-consistent dynamics around mass-growing MBHs remain largely unexplored. In this work, we simulate nuclear star clusters (NSCs) across a range of masses and density profiles by employing the GNC Monte Carlo code, which self-consistently models stellar dynamics and the subsequent accretion of released gas. We find that stellar collisions flatten the density cusp in the innermost regions ( r ≲ 10 ⁻³ −10 ⁻² pc) within ∼0.1−1 Gyr. While high initial collision rates in steep cusps quickly decline due to stellar depletion, the interplay between collisions and MBH growth is important only in massive NSCs ( M ⋆ ∼ 10 ⁹ M ⊙ ). As MBH grows, increased stellar velocities shift the balance toward destructive collisions, the relative velocities of which can be ≳2500 km s ⁻¹ . Consequently, present-day destructive collision rates in massive clusters remain high (10 ⁻⁴ ∼ 10 ⁻³ yr ⁻¹ ), whereas they are smaller in Milky Way–like NSCs or negligible in smaller NSCs. Our results highlight a crucial synergy between stellar dynamics and MBH growth, identifying massive galaxies as prime targets for observing transients from destructive stellar collisions.
Related
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BibTeX
@article{zhang2026stellar,
title = {{Stellar Collisions from Self-consistent Stellar Dynamics around Growing Supermassive Black Holes}},
author = {Fupeng Zhang and Pau Amaro Seoane},
journal = {The Astrophysical Journal},
year = {2026},
month = oct,
doi = {10.3847/1538-4357/aeac13},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aeac13},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Stellar Collisions from Self-consistent Stellar Dynamics around Growing Supermassive Black Holes
AU - Fupeng Zhang
AU - Pau Amaro Seoane
PY - 2026
DA - 2026/10/30
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aeac13
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aeac13
AB - The centers of galaxies harbor the densest stellar environments, where a massive black hole (MBH) accelerates stars to such high velocities that direct collisions can result in high-energetic phenomena, such as gravitational wave sources, kilonovae, and supernova-like transients. These collisions can reshape the cluster’s density profile and release gas that can be subsequently accreted by the MBH. However, the evolving rates of such phenomena from self-consistent dynamics around mass-growing MBHs remain largely unexplored. In this work, we simulate nuclear star clusters (NSCs) across a range of masses and density profiles by employing the GNC Monte Carlo code, which self-consistently models stellar dynamics and the subsequent accretion of released gas. We find that stellar collisions flatten the density cusp in the innermost regions ( r ≲ 10 ⁻³ −10 ⁻² pc) within ∼0.1−1 Gyr. While high initial collision rates in steep cusps quickly decline due to stellar depletion, the interplay between collisions and MBH growth is important only in massive NSCs ( M ⋆ ∼ 10 ⁹ M ⊙ ). As MBH grows, increased stellar velocities shift the balance toward destructive collisions, the relative velocities of which can be ≳2500 km s ⁻¹ . Consequently, present-day destructive collision rates in massive clusters remain high (10 ⁻⁴ ∼ 10 ⁻³ yr ⁻¹ ), whereas they are smaller in Milky Way–like NSCs or negligible in smaller NSCs. Our results highlight a crucial synergy between stellar dynamics and MBH growth, identifying massive galaxies as prime targets for observing transients from destructive stellar collisions.
SN - 1538-4357
SN - 0004-637X
ER -