AI 中文总结
研究宇宙学背景下三轴星系形状对三重超大质量黑洞动力学的影响，通过高分辨率引力动力学N体模拟，探索多种轨道构型和宿主星系形状，发现两重黑洞先合并，第三个黑洞有不同情况，且星系初始三轴形状对三重系统最终动力学结果影响不大。
AI 中文摘要
在Λ冷暗物质（ΛCDM）宇宙学框架模型中，星系形成的层级性质常导致星系核中存在多个超大质量黑洞（SMBHs）。星系合并的时间尺度对其中心SMBHs的动力学演化和合并动力学起着关键作用。虽然双星SMBH演化已被广泛研究，但三重SMBH系统的长期动力学，尤其是在现实的非球形星系势场中，仍了解较少。本文利用高分辨率引力动力学N体模拟，研究了取自ROMULUS25宇宙学模拟、嵌入三轴恒星背景中的三个SMBH三重系统动力学演化中三轴性的作用，探索了一系列轨道构型和宿主星系形状，追踪从星系吸积到亚秒差距分离处硬双星形成的轨道演化，并利用观测到的硬化率估计合并时间。结果表明，两个最重的黑洞形成一个有效硬化的双星，在哈勃时间内合并，而第三个黑洞要么与较重的双星形成稳定的层级三重系统，要么留在宽的星系轨道上。最后分析了模拟中星系遗迹的三轴性，得出星系的初始三轴形状不会显著改变三重系统最终动力学结果的结论。
英文摘要
The hierarchical nature of galaxy formation in the Lambda cold dark matter ($Λ$CDM) cosmological framework model often leads to the presence of multiple supermassive black holes (SMBHs) in the galactic nuclei. The timescale over which galaxies merge plays a crucial role in shaping the dynamical evolution and the merger dynamics of their central SMBHs. While binary SMBH evolution has been extensively studied, the long-term dynamics of triple SMBH systems, especially in realistic, nonspherical galactic potentials, still remain less understood. In this work, we investigated the role of triaxiality in shaping the dynamical evolution of three SMBH triple systems taken from the ROMULUS25 cosmological simulation embedded in triaxial stellar backgrounds to find common dynamical evolution patterns and estimate typical coalescence times using high-resolution gravitodynamical $\textit{N}$-body simulations. We explored a range of orbital configurations and host galaxy shapes with initial conditions from the ROMULUS25 data and tracked the orbital evolution from the galactic inspiral to the formation of hard binaries at sub-parsec separations and used the observed hardening rates to estimate the time of coalescence. In all cases, the two heaviest black holes form an efficiently hardening binary, which merges within the Hubble time, while the third black hole (BH) either forms a stable hierarchical triple system with the heavier binary or remains on a wide galactic orbit. Finally, we analyzed the triaxiality of the galactic remnant from our simulations and conclude that the initial triaxial shape of the galaxies does not significantly change the final dynamical outcome of the triple systems.
Comments13 pages, 5 figures, accepted for publication in A&A
