Binary black hole (BBH) mergers, particularly those with component masses in the pair-instability gap, may be produced by hierarchical mergers in the disks surrounding Active Galactic Nuclei (AGNs). While the interaction of an embedded BBH with an AGN disk is typically assumed to facilitate a merger, recent high-resolution hydrodynamical simulations challenge this assumption. However, these simulations often have simplified treatments for gas thermodynamics. In this work, we model the possible consequence of various feedback from an embedded BBH with a simple model that maintains an enhanced temperature profile around each binary component. We show that when the minidisks around each BH become hotter than the background by a factor of three, the BBH orbital evolution switches from expansion to contraction. By analyzing the gravitational torque profile, we find that this change in direction is driven by a weakening of the minidisk spirals and their positive torque on the binary. Our results highlight the important role of thermodynamics around BBHs and its effect on their orbital evolution, suggesting that AGN disks could be efficient factories for BBH mergers.

中文翻译：

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热环状单盘驱动活跃星系核盘中的双星黑洞合并

双黑洞 (BBH) 并合，特别是那些在对-不稳定间隙中具有分量质量的双星黑洞 (BBH) 并合，可能是由活动星系核 (AGN) 周围的盘中的分层合并产生的。虽然嵌入式 BBH 与 AGN 盘的相互作用通常被认为有助于合并，但最近的高分辨率流体动力学模拟挑战了这一假设。然而，这些模拟通常简化了气体热力学的处理。在这项工作中，我们使用一个简单的模型对来自嵌入式 BBH 的各种反馈的可能结果进行建模，该模型在每个二进制组件周围保持增强的温度分布。我们表明，当每个 BH 周围的迷你盘变得比背景热三倍时，BBH 轨道演化从膨胀转变为收缩。通过分析重力扭矩曲线，我们发现这种方向变化是由微型盘螺旋的减弱及其对双星的正扭矩驱动的。我们的结果突出了热力学在 BBH 周围的重要作用及其对其轨道演化的影响，表明 AGN 盘可能是 BBH 合并的有效工厂。