AI 中文总结
该研究分析AGN盘中“不朽”恒星与致密天体的相互作用，发现盘内双黑洞并合的特征信号处于分赫兹波段，相关并合率最高可达约8 Gpc⁻³ yr⁻¹，需DECIGO等下一代探测器探测。
AI 中文摘要
吸积到大质量黑洞上的气体盘为活动星系核（AGN）提供能量，这类气体盘可从核星团捕获恒星，或通过引力不稳定性在原地形成恒星。致密、高温的盘环境会驱动嵌入恒星的快速吸积，显著改变其演化。模型预测，若吸积足够快，新鲜气体补充恒星核心氢的速度与其燃烧速度相当，恒星将达到准稳态。本文研究这类大质量、长寿命（“不朽”）恒星与AGN盘中致密天体的相遇，估算单次致密残余物螺旋进入AGN恒星的相遇率和时标；根据反馈对后续吸积的调控强度，恒星要么在类似坍缩星的引擎驱动暂现源中被吞噬，要么转变为包含中心黑洞的长寿命准恒星状天体。随后研究AGN恒星内的双黑洞（BBH）并合，发现气体阻力使双黑洞并合的硬化速度远快于仅靠引力波辐射的情况，该并合是LIGO-Virgo-KAGRA（LVK）的强信号源，但致密环境的特征印记——相对于真空的强抑制和并合相位偏移——处于分赫兹（deci-Hz）波段而非毫赫兹（milli-Hz）的LISA波段，需下一代探测器如DECIGO才能最佳分辨。估算该通道在有利场景下的BBH并合率可达约8 Gpc⁻³ yr⁻¹，并讨论模型不确定性与未来研究方向。
英文摘要
Disks of gas accreting onto supermassive black holes, powering active galactic nuclei (AGN), can capture stars from nuclear star clusters or form stars in situ via gravitational instability. The dense, hot disk environment can drive rapid accretion onto embedded stars, dramatically altering their evolution. Models predict that, for sufficiently rapid accretion, fresh gas replenishes hydrogen in stellar cores as quickly as it is burned, and the stars reach a quasi-steady state. Here we study encounters of such massive, long-lived (''immortal'') stars with compact objects in AGN disks. We estimate the encounter rate and the timescale for a single compact remnant to spiral into an AGN star; depending on how strongly feedback regulates the ensuing accretion, the star is either consumed in a collapsar-like, engine-driven transient or converted into a long-lived, quasi-star-like object hosting a central black hole. We then study the merger of a binary black hole (BBH) inside the AGN star, and show that gas drag hardens the binary to merger far faster than gravitational-wave emission alone. The resulting merger is a loud LIGO-Virgo-KAGRA (LVK) source, but the characteristic imprint of the dense environment -a strong suppression and dephasing of the inspiral relative to vacuum- falls in the deci-Hz band rather than the milli-Hz LISA band, and is best resolved by next-generation detectors such as DECIGO. We estimate that this channel could contribute a BBH merger rate of up to $\sim8\,{\rm Gpc^{-3}\,yr^{-1}}$ in favorable scenarios, and discuss the model uncertainties and directions for future work.
Comments22 pages, 9 figures, Submitted to ApJ
