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arXiv 2602.21065astro-ph.HEgr-qcphysics.space-ph
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在潮汐破坏事件AT2020afhd中‘无发定理’的作用

The no-hair theorems at work in the tidal disruption event AT2020afhd

Ministero dell’ Istruzione e del Merito(教育与卓越部)

Lorenzo Iorio

AI总结:

研究通过分析AT2020afhd事件中吸积盘和喷流的周期性运动,验证了广义相对论中的引力磁学Lense-Thirring进动效应,揭示了黑洞自旋参数的限制范围及非相对论性模型的扩展可能性。

摘要:

最近,与光学暂现体AT2020afhd相关的潮汐破坏事件中,由超大质量黑洞驱动的吸积盘和喷流的共进动现象,在X射线和无线电波段分别被独立测量,显示出约300天内近20天的周期性。一个分析模型解释了广义相对论中引力磁学Lense-Thirring进动效应,给出了系统参数空间中的允许区域,与文献中广义相对论磁流体动力学模拟的结果基本一致。当前的分析方法可以扩展以包括黑洞四极矩质量矩的进动效应。该方法在仅考虑Lense-Thirring效应时,消除了自旋参数正负值在允许区域中的退化现象。黑洞质量的最佳估计给出了自旋参数的范围$0.185-0.215$。使用相同的策略,考虑有限大小的扩展盘和参数化幂律质量密度的引力磁学频率,得出每个幂律指数值对应的允许区域通常是不同的且不重叠的。

英文摘要:

Recently, the coprecession of both the accretion disk and the jet formed following the tidal disruption event associated with the optical transient AT2020afhd, driven by a supermassive black hole of almost ten million solar masses, were independently measured in both the X and radio bands, respectively, showing a periodicity of nearly 20 days over about 300 days. An analytical model of the general relativistic gravitomagnetic Lense-Thirring precession of the effective orbit of a fictitious test particle revolving about a spinning primary can explain the observed precessional features. It yields allowed regions in the system's parameter space which, as far as the hole's dimensionless spin parameter is concerned, are essentially in agreement with those obtained in the literature with general relativistic magnetohydrodynamic simulations. The present analytical approach can be extended to include the precession due to the hole's quadrupole mass moment as well. It breaks the degeneracy in the allowed regions occurring for negative and positive values of the spin parameter when only the Lense-Thirring effect is considered. The best estimate for the hole's mass yields the range $0.185-0.215$ for the dimensionless spin parameter. Using the same strategy with the gravitomagnetic frequency for an extended disk of finite size with a parameterized power-law mass density yields to distinct, generally non-overlapping allowed regions for each value of the power-law index adopted.

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