Quantifying collision-driven mass loss in supermassive star formation: the role of stellar structure and accretion
Abstract
Observations of high-redshift galaxies with JWST have renewed interest in scenarios where supermassive stars form via runaway stellar collisions in dense clusters, yet the impact of collision-driven mass loss on their growth remains uncertain. In this work, we perform a post-processing analysis of 3D hydrodynamical simulations of the formation of a supermassive star, applying an analytic mass-loss prescription to stellar collisions while exploring different assumptions for the internal stellar structure. We consider a polytropic main-sequence model, a semi-analytic accreting protostar model, and structures derived from stellar evolution calculations. We find that the cumulative mass-loss fraction depends sensitively on the adopted stellar structure, ranging from ≲ 10−25% for more compact configurations to ≳ 30−40% for more extended protostellar models. The importance of mass loss further depends on the dynamical state of the system, including the ratio of stellar velocity dispersion to the stellar surface escape velocity. We find significant uncertainty depending on the prescription used. As a result, collision-driven mass loss could significantly limit the growth of the central object, at least in some cases. Overall, our results indicate that uncertainties in the internal structure of rapidly accreting protostars represent a major source of systematic uncertainty and must be better constrained to robustly assess the viability of runaway-collision pathways for forming massive black hole seeds.
Related
- From Dense Gas Clouds to Supermassive Black Hole Seeds: Hybrid Hydro/Direct N-body Simulations of Runaway Collision-driven Intermediate-mass Black Hole Formation
- Chaotic accretion can (still) explain early supermassive black hole growth
- Constraining Supermassive Black Hole Seeding and Accretion via Occupation Fractions and Mass-Weighted Distributions
- Magnetized Accretion Flows with Low Angular Momentum Around Supermassive Black Holes
- Chaotic accretion can (still) explain early supermassive black hole growth
BibTeX
@misc{solar2026quantifying,
title = {{Quantifying collision-driven mass loss in supermassive star formation: the role of stellar structure and accretion}},
author = {P. A. Solar and B. Reinoso and D. R. G. Schleicher and R. Banerjee},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.04892},
eprint = {2609.04892},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.04892},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Quantifying collision-driven mass loss in supermassive star formation: the role of stellar structure and accretion
AU - P. A. Solar
AU - B. Reinoso
AU - D. R. G. Schleicher
AU - R. Banerjee
PY - 2026
DA - 2026/09/04
PB - arXiv
DO - 10.48550/arxiv.2609.04892
UR - https://arxiv.org/abs/2609.04892
AB - Observations of high-redshift galaxies with JWST have renewed interest in scenarios where supermassive stars form via runaway stellar collisions in dense clusters, yet the impact of collision-driven mass loss on their growth remains uncertain. In this work, we perform a post-processing analysis of 3D hydrodynamical simulations of the formation of a supermassive star, applying an analytic mass-loss prescription to stellar collisions while exploring different assumptions for the internal stellar structure. We consider a polytropic main-sequence model, a semi-analytic accreting protostar model, and structures derived from stellar evolution calculations. We find that the cumulative mass-loss fraction depends sensitively on the adopted stellar structure, ranging from ≲ 10−25% for more compact configurations to ≳ 30−40% for more extended protostellar models. The importance of mass loss further depends on the dynamical state of the system, including the ratio of stellar velocity dispersion to the stellar surface escape velocity. We find significant uncertainty depending on the prescription used. As a result, collision-driven mass loss could significantly limit the growth of the central object, at least in some cases. Overall, our results indicate that uncertainties in the internal structure of rapidly accreting protostars represent a major source of systematic uncertainty and must be better constrained to robustly assess the viability of runaway-collision pathways for forming massive black hole seeds.
ER -