标题： 双星与其周围盘的解耦 显示英文标题

标题： The Decoupling of Binaries from Their Circumbinary Disks

摘要： 我们从分析和数值上研究了由于引力辐射而逐渐靠近的超大质量黑洞双星，以阐明双星与其盘之间的解耦，并为未来这些系统的多信使观测提供信息。 我们的数值研究从初始分离为$100 GM/c^2$的等质量双星开始，直到合并为止，分辨率可达$\sim0.04 GM/c^2$，其中$M$是总双星质量。 我们的模拟准确捕捉到每个双星轨道演化与周围盘解耦的时刻，并精确解析了整个逐渐靠近过程中的气体流动。 我们通过分析和数值计算表明，基于时间尺度的预测高估了解耦发生的双星分离距离，低估了$\sim3$倍，并展示了基于速度的解耦标准的实用性。 高粘性（$\nu\gtrsim0.03 GM/c$）周围的双星系统解耦较晚（$a_b\lesssim 15 GM/c^2$），并在接近合并时具有与恒定双星分离的周围盘相似的形态。 低粘性的周围盘解耦较早，并表现出定性不同的吸积流，这导致双星上的吸积急剧减少。 如果被探测到，这种减少可能会明确识别出在LISA误差体积内的正在进行事件的宿主星系。 我们展示了吸积幅度和变化如何随着双星逐渐从周围盘解耦而演变，并且在LISA频带内的双星逐渐靠近过程中，解耦发生的位置。 我们证明，即使动态上可以忽略不计，气体也可能在引力波相位上留下可检测的印记。 显示英文摘要

摘要： We have investigated, both analytically and numerically, accreting supermassive black hole binaries as they inspiral due to gravitational radiation to elucidate the decoupling of binaries from their disks and inform future multi-messenger observations of these systems. Our numerical studies evolve equal-mass binaries from initial separations of $100 GM/c^2$ until merger, resolving scales as small as $\sim0.04 GM/c^2$, where $M$ is the total binary mass. Our simulations accurately capture the point at which the orbital evolution of each binary decouples from that of their circumbinary disk, and precisely resolve the flow of gas throughout the inspiral. We demonstrate analytically and numerically that timescale-based predictions overestimate the binary separations at which decoupling occurs by factors of $\sim3$, and illustrate the utility of a velocity-based decoupling criterion. High-viscosity ($\nu\gtrsim0.03 GM/c$) circumbinary systems decouple late ($a_b\lesssim 15 GM/c^2$) and have qualitatively similar morphologies near merger to circumbinary systems with constant binary separations. Lower-viscosity circumbinary disks decouple earlier and exhibit qualitatively different accretion flows, which lead to precipitously decreasing accretion onto the binary. If detected, such a decrease may unambiguously identify the host galaxy of an ongoing event within a LISA error volume. We illustrate how accretion amplitude and variability evolve as binaries gradually decouple from their circumbinary disks, and where decoupling occurs over the course of binary inspirals in the LISA band. We show that, even when dynamically negligible, gas may leave a detectable imprint on the phase of gravitational waves.