When two galaxies merge, they often produce a supermassive black hole binary (SMBHB) at their center. Numerical simulations with stars and cold dark matter show that SMBHBs typically stall out at a distance of a few parsecs apart and take billions of years to coalesce. This is known as the final parsec problem. We suggest that ultralight dark matter (ULDM) halos around SMBHBs can generate dark matter waves due to dynamical friction. These waves can effectively carry away orbital energy from the black holes, rapidly driving them together. To test this hypothesis, we performed numerical simulations of black hole binaries inside ULDM halos. Due to gravitational cooling and quasi-normal modes, the loss-cone problem can be avoided. The decay time scale gives lower bounds on masses of the ULDM particles and SMBHBs comparable to observational data. Our results imply that ULDM waves can lead to the rapid orbital decay of black hole binaries.

中文翻译：

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黑洞合并和超轻暗物质的最终秒差距问题


当两个星系合并时，它们通常会在中心产生一个超大质量黑洞双星（SMBHB）。对恒星和冷暗物质的数值模拟表明，SMBHB 通常会在相距几秒差距的距离内失速，并需要数十亿年才能合并。这被称为最终秒差距问题。我们认为，SMBHB 周围的超轻暗物质 (ULDM) 晕可以由于动态摩擦而产生暗物质波。这些波可以有效地从黑洞带走轨道能量，迅速将它们驱动到一起。为了验证这一假设，我们对 ULDM 晕内的黑洞双星进行了数值模拟。由于重力冷却和准正规模式，可以避免损失锥问题。衰减时间尺度给出了与观测数据相当的 ULDM 粒子和 SMBHB 质量的下限。我们的结果表明 ULDM 波可以导致黑洞双星的快速轨道衰变。