On the Diversity of Fallback Rates from Tidal Disruption Events with Accurate Stellar Structure
On the Diversity of Fallback Rates from Tidal Disruption Events with Accurate Stellar Structure
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DOI：
10.3847/2041-8213/ab380d
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发表时间：
2019-07
期刊：
影响因子：
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通讯作者：
E. Golightly;C. Nixon;E. Coughlin
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文献类型：
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作者：
E. Golightly;C. Nixon;E. Coughlin
超大质量黑洞（SMBH）对恒星的潮汐破坏可以用来探测SMBH质量函数、单个恒星的性质以及星系核中的恒星动力学。即将到来的任务将探测到数千个潮汐中断事件（TDE），需要精确的理论建模来精确解释数据。在这里，我们分析了更现实的恒星结构对TDE结果的影响;特别是，我们比较了回落率，即潮汐破坏碎片返回黑洞的速率，从恒星演化代码梅萨和γ = 5/3多面体产生的祖先。我们发现，台面产生的密度分布产生质的不同的回落率相比，多方近似，只有回落曲线从低质量（1 M或更少），零年龄主序星是很好的适合无论是一个或5/3多方。恒星年龄对回落曲线的形状有很大的影响，并且可以产生特征时间尺度（例如，到回退速率的峰值的时间）与多变值有很大不同。我们使用这些差异来评估从观测到的光变曲线推断的黑洞质量与真实值的偏离程度，并发现这种差异可以达到数量级水平。精确的恒星结构也会导致星星完全破碎的临界撞击参数发生很大变化，并会增加碎片流在自身重力作用下碎裂的可能性。这些结果表明，需要详细的建模，以准确地解释所观察到的TDEs的光变曲线。
The tidal disruption of stars by supermassive black holes (SMBHs) can be used to probe the SMBH mass function, the properties of individual stars, and stellar dynamics in galactic nuclei. Upcoming missions will detect thousands of tidal disruption events (TDEs), and accurate theoretical modeling is required to interpret the data with precision. Here we analyze the influence of more realistic stellar structure on the outcome of TDEs; in particular, we compare the fallback rates—being the rate at which tidally disrupted debris returns to the black hole—from progenitors generated with the stellar evolution code mesa to and γ = 5/3 polytropes. We find that mesa-generated density profiles yield qualitatively different fallback rates as compared to polytropic approximations, and that only the fallback curves from low-mass (1 M⊙ or less), zero-age main-sequence stars are well fit by either a or 5/3 polytrope. Stellar age has a strong affect on the shape of the fallback curve, and can produce characteristic timescales (e.g., the time to the peak of the fallback rate) that greatly differ from the polytropic values. We use these differences to assess the degree to which the inferred black hole mass from the observed light curve can deviate from the true value, and find that the discrepancy can be at the order of magnitude level. Accurate stellar structure also leads to a substantial variation in the critical impact parameter at which the star is fully disrupted, and can increase the susceptibility of the debris stream to fragmentation under its own self-gravity. These results suggest that detailed modeling is required to accurately interpret observed light curves of TDEs.