与轴对称主星系发生次并合的卫星星系潮汐瓦解的有效模型
An effective model for the tidal disruption of satellites undergoing minor mergers with axisymmetric primaries
AI总结：
针对次并合中星系潮汐剥离质量损失建模不足的问题，提出一种适用于轴对称势的新颖有效模型，经N体模拟验证在多种星系参数下均表现良好，为半解析计算提供了有力补充。
摘要：
根据分层形成范式，星系通过较小实体的并合形成，而潜伏在它们中心的大质量黑洞（MBHs）会迁移到新星系的核区，在那里形成双星系统。MBH双星的形成和演化，特别是它们的并合时标，对于旨在探测接近并合时MBH产生的引力波信号的当前和未来设施来说非常重要。虽然针对该过程的大多数研究基于流体动力学模拟，但高昂的计算成本使得完整的参数空间探索变得不可行。半解析方法是一种有效的替代方案，但它们需要针对次并合中并合星系因潮汐剥离导致的质量损失提供特定方案，而这一点通常未被考虑，或者至多在假设非常理想化的几何形状下进行建模。在这项工作中，我们提出了一个新颖且有效的轴对称势潮汐剥离模型，可应用于半解析模型中。我们通过N体模拟验证了我们的半解析方法，考虑了不同的星系大小、倾角和偏心率，发现其仅对轨道偏心率有中等程度的依赖。特别是，我们发现，对于近圆轨道，我们的模型略微高估了质量损失，这是由于质量被移除后恒星分布的调整所致。尽管如此，该模型在所有考虑的条件下均与模拟表现出极好的一致性，因此是对半解析计算的一项极其强大的补充。
英文摘要：
According to the hierarchical formation paradigm, galaxies form through mergers of smaller entities and massive black holes (MBHs), if lurking at their centers, migrate to the nucleus of the newly formed galaxy, where they form binary systems. The formation and evolution of MBH binaries, and in particular their coalescence timescale, is very relevant for current and future facilities aimed at detecting the gravitational-wave signal produced by the MBH close to coalescence. While most of the studies targeting this process are based on hydrodynamic simulations, the high computational cost makes a complete parameter space exploration prohibitive. Semi-analytic approaches represent a valid alternative, but they require ad-hoc prescriptions for the mass loss of the merging galaxies in minor mergers due to tidal stripping, which is not commonly considered or at most modelled assuming very idealised geometries. In this work, we propose a novel, effective model for the tidal stripping in axisymmetric potentials, to be implemented in semi-analytic models. We validate our semi-analytic approach against N-body simulations considering different galaxy sizes, inclinations, and eccentricities, finding only a moderate dependence on the orbit eccentricity. In particular, we find that, for almost circular orbits, our model mildly overestimates the mass loss, and this is due to the adjustment of the stellar distribution after the mass is removed. Nonetheless, the model exhibits a very good agreement with simulations in all the considered conditions, and thus represents an extremely powerful addition to semi-analytic calculations.
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