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arXiv 2202.07668astro-ph.HE
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致密超大质量黑洞双星的潮汐扰动事件

Tidal Disruption Events by Compact Supermassive Black Hole Binaries

Taeho Ryu, Alessandro A. Trani, Nathan W. C. Leigh

摘要:

恒星可能会被超大质量黑洞双星潮汐摧毁或吞噬。利用大量精确的少体模拟,我们研究了硬超大质量黑洞双星对完全和部分破裂以及直接俘获事件的增强和抑制,主黑洞质量($10^{5}-10^{8}M_{\odot}$)、双星质量比($10^{-3}-1$)、双星半长轴与硬化半径之比($10^{-4}-1$)、双星偏心率($0.0-0.9$)和恒星质量($0.3-3M_{\odot}$)。这是一个显着的扩展参数空间相比,以前的工作。我们发现,所有三个事件的遭遇概率很好地描述了遭遇横截面,这是成比例的近心距离。相对于单个黑洞,超大质量黑洞双星的完全破裂概率可以增加$40-50$的1倍或抑制$10$的1倍,这取决于双星的参数。相对论效应对于主黑洞质量$\leq 10^{7}M_{\odot}$并不重要,但是对于更高的主黑洞质量,相对论效应可以提供小于$2-3$的因子的完全破裂概率的额外增强。给出了适用于宽参数范围的硬超大质量黑洞双星完全破裂概率的拟合公式。我们还发现,部分中断事件可以发生多次完全中断或直接捕获之前,其概率可以大于完全中断事件的三倍。由于部分破裂事件可以引起恒星自旋和质量损失并改变轨道,因此它可以显着影响整体完全破裂事件率和光变曲线的形状。

英文摘要:

Stars can be tidally destroyed or swallowed by supermassive black hole binaries. Using a large number of accurate few-body simulations, we investigate the enhancement and suppression of full and partial disruption and direct capture events by hard supermassive black hole binaries with a wide ranges of key parameters, i.e., the primary black hole mass ($10^{5}-10^{8}M_{\odot}$), the binary mass ratio ($10^{-3}-1$), the ratio of the binary semimajor axis to the hardening radius ($10^{-4}-1$), the binary eccentricity ($0.0-0.9$) and the stellar mass ($0.3-3M_{\odot}$). This is a significant extension of the parameter space compared to previous work. We show that the encounter probabilities of all three events are well-described by the encounter cross section, which is proportional to the pericenter distance. The probability of full disruptions by supermassive black hole binaries can be enhanced by up to a factor of $40-50$ or suppressed by up to a factor of $10$, relative to that by single black holes, depending on the binary parameters. Relativistic effects are not important for the primary black hole mass $\leq 10^{7}M_{\odot}$, but can provide an additional enhancement of the full disruption probability by less than a factor of $2-3$ for higher primary black hole masses. We provide a fitting formula for the full disruption probability by the hard supermassive black hole binaries that works for a wide range of parameters. We also find that partial disruption events can occur multiple times before full disruptions or direct captures, and their probabilities can be greater than that of full disruption events by a factor of three. Because partial disruption events can induce stellar spins and mass loss and change the orbits, it can significantly affect the overall full disruption event rate and the shape of the light curves.

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