Orbital Migration of Interacting Stellar Mass Black Holes in Disks around Supermassive Black Holes
Orbital Migration of Interacting Stellar Mass Black Holes in Disks around Supermassive Black Holes
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DOI：
10.3847/1538-4357/ab20ca
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发表时间：
2019
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影响因子：
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通讯作者：
Amy Secunda;J. Bellovary;M. M. Low-M.;K. Ford;B. McKernan;N. Leigh;W. Lyra;Z. Sándor
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文献类型：
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作者：
Amy Secunda;J. Bellovary;M. M. Low-M.;K. Ford;B. McKernan;N. Leigh;W. Lyra;Z. Sándor
由高级激光干涉引力波天文台（LIGO）推断的恒星质量黑洞双星（sBHB）的合并率表明需要一个有效的sBHB形成源。活动星系核（AGN）盘是一个很有前途的位置，形成这些sBHB，以及其他紧凑的物体的二进制文件，因为强大的扭矩所施加的气体盘。这些气体扭矩导致轨道紧凑的物体向向内和向外扭矩抵消的区域迁移，称为迁移陷阱。我们模拟迁移的恒星质量黑洞的一个例子中的模型AGN磁盘，使用增强的N体代码，包括迁移扭矩的解析近似，随机引力施加的湍流密度波动在磁盘上，倾斜和偏心阻尼产生的通道通过气体盘，除了标准的物体之间的引力。我们发现，sBHBs形式迅速在我们的模型磁盘作为恒星质量的黑洞迁移到迁移陷阱。这些sBHB可能随后在短时间内合并。这一过程继续下去，导致了一群超大质量恒星质量黑洞的形成。活动星系核盘中sBHB的形成可能对LIGO推测的sBHB合并率有重要贡献。
The merger rate of stellar-mass black hole binaries (sBHBs) inferred by the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) suggests the need for an efficient source of sBHB formation. Active galactic nucleus (AGN) disks are a promising location for the formation of these sBHBs, as well as binaries of other compact objects, because of powerful torques exerted by the gas disk. These gas torques cause orbiting compact objects to migrate toward regions in the disk where inward and outward torques cancel, known as migration traps. We simulate the migration of stellar mass black holes in an example of a model AGN disk, using an augmented N-body code that includes analytic approximations to migration torques, stochastic gravitational forces exerted by turbulent density fluctuations in the disk, and inclination and eccentricity dampening produced by passages through the gas disk, in addition to the standard gravitational forces between objects. We find that sBHBs form rapidly in our model disk as stellar-mass black holes migrate toward the migration trap. These sBHBs are likely to subsequently merge on short timescales. The process continues, leading to the build-up of a population of over-massive stellar-mass black holes. The formation of sBHBs in AGN disks could contribute significantly to the sBHB merger rate inferred by LIGO.