Hydrodynamics of Collisions and Close Encounters between Stellar Black Holes and Main-sequence Stars
Hydrodynamics of Collisions and Close Encounters between Stellar Black Holes and Main-sequence Stars
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DOI：
10.3847/1538-4357/ac714f
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发表时间：
2022-01
期刊：
影响因子：
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通讯作者：
K. Kremer;J. Lombardi;Wenbin Lu;A. Piro;F. Rasio
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文献类型：
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作者：
K. Kremer;J. Lombardi;Wenbin Lu;A. Piro;F. Rasio
最近的分析表明，恒星和恒星黑洞之间的近距离接触经常发生在密集的星星星团中。根据最接近的距离，这些相互作用可能导致耗散遭遇，如潮汐捕获和破坏，或直接物理碰撞，所有这些都可能伴随着明亮的电磁瞬变。在这项研究中，我们进行了广泛的流体动力学模拟黑洞和主序星之间的近距离接触，共同覆盖感兴趣的参数空间，我们确定和分类的各种可能的结果。在几乎是正面碰撞的情况下，星星被完全破坏，大约一半的恒星物质被束缚在黑洞上。在经典潮汐破裂半径附近的更远的相遇中，星星在第一次近心通过时只被部分地破裂。根据相互作用的细节，部分被破坏的恒星残骸可能被黑洞潮汐捕获或变得不受约束（在某些情况下，从不对称的质量损失中接收足够大的脉冲踢出其宿主星团）。在前一种情况下，星星在最终被完全破坏之前将经历额外的近心通道。基于在我们的模拟结束时绑定到黑洞的材料的属性（特别是，总的绑定质量和角动量），我们评论预期的吸积过程和相关的电磁签名可能会导致。
Recent analyses have shown that close encounters between stars and stellar black holes occur frequently in dense star clusters. Depending upon the distance at closest approach, these interactions can lead to dissipating encounters such as tidal captures and disruptions, or direct physical collisions, all of which may be accompanied by bright electromagnetic transients. In this study, we perform a wide range of hydrodynamic simulations of close encounters between black holes and main-sequence stars that collectively cover the parameter space of interest, and we identify and classify the various possible outcomes. In the case of nearly head-on collisions, the star is completely disrupted with roughly half of the stellar material becoming bound to the black hole. For more distant encounters near the classical tidal-disruption radius, the star is only partially disrupted on the first pericenter passage. Depending upon the interaction details, the partially disrupted stellar remnant may be tidally captured by the black hole or become unbound (in some cases, receiving a sufficiently large impulsive kick from asymmetric mass loss to be ejected from its host cluster). In the former case, the star will undergo additional pericenter passages before ultimately being disrupted fully. Based on the properties of the material bound to the black hole at the end of our simulations (in particular, the total bound mass and angular momentum), we comment upon the expected accretion process and associated electromagnetic signatures that are likely to result.