发表机构
Hamburger Sternwarte, Universität Hamburg; University of Helsinki; Sapienza Università di Roma（汉堡天文台，汉堡大学; 赫尔辛基大学; 罗马智慧大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过对超大质量恒星形成的三维流体动力学模拟进行后处理分析，发现碰撞驱动的质量损失程度高度依赖于恒星内部结构，该不确定性是评估失控碰撞路径形成大质量黑洞种子可行性的主要障碍。
AI 中文摘要
詹姆斯·韦布空间望远镜（JWST）对高红移星系的观测，重新引发了人们对“超大质量恒星通过致密星团中失控恒星碰撞形成”这一情景的兴趣，但碰撞驱动的质量损失对其增长的影响仍不确定。本研究对超大质量恒星形成的三维流体动力学模拟进行后处理分析，采用解析质量损失方案处理恒星碰撞，同时探索不同的恒星内部结构假设：包括多方主序模型、半解析吸积原恒星模型，以及由恒星演化计算得到的结构。研究发现，累积质量损失分数高度依赖于所采用的恒星结构：更致密的结构对应质量损失分数约为10%-25%，更延展的原恒星模型则对应质量损失分数约为30%-40%。质量损失的重要性还取决于系统的动力学状态，包括恒星速度弥散与恒星表面逃逸速度的比值，且不同方案带来的不确定性显著。因此，碰撞驱动的质量损失可能会在某些情况下显著限制中心天体的增长。总体而言，本研究结果表明，快速吸积原恒星内部结构的不确定性是系统误差的主要来源，必须更好地约束该不确定性，才能可靠评估失控碰撞路径形成大质量黑洞种子的可行性。
英文摘要
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 $\lesssim 10-25\%$ for more compact configurations to $\gtrsim 30-40\%$ 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.
