近日，美国麻省理工学院的Dheeraj R. Pasham及其研究团队取得一项新进展。经过不懈努力，他们揭示了超大质量黑洞破坏恒星后的透镜-蒂林进动。相关研究成果已于2024年5月22日在国际权威学术期刊《自然》上发表。

据悉，当一颗恒星被超大质量黑洞摧毁后，其周围形成的吸积盘最初可能与黑洞的赤道面不在同一平面上。这种错位现象会在星盘上引发相对论扭矩（即透镜-蒂林效应），从而导致星盘在早期阶段发生进动。然而，随着时间的推移，星盘最终会与黑洞的赤道面对齐，从而终止其进动过程。

该研究团队通过高频率的X射线监测，观察到了潮汐中断事件（TDE）中强烈的、准周期性的X射线通量和温度调制。这些X射线调制大约每15天出现一次，并在TDE的早期阶段持续了约130天。尽管吸积流的透镜-蒂林进动可能是这种X射线变化的原因之一，但也不能排除其他物理机制，如辐射压力不稳定性。基于典型的TDE参数，即一颗类似太阳的恒星，其形成的星盘延伸至所谓的圆化半径，且星盘作为刚体进行进动，研究人员将黑洞的扰动无量纲自旋参数限制在0.05≤∣a∣≤0.5的范围内。

附：英文原文

Title: Lense–Thirring precession after a supermassive black hole disrupts a star

Author: Pasham, Dheeraj R., Zajaek, Michal, Nixon, C. J., Coughlin, Eric R., Sniegowska, Marzena, Janiuk, Agnieszka, Czerny, Boena, Wevers, Thomas, Guolo, Muryel, Ajay, Yukta, Loewenstein, Michael

Issue&Volume: 2024-05-22

Abstract: An accretion disk formed around a supermassive black hole after it disrupts a star is expected to be initially misaligned with respect to the equatorial plane of the black hole. This misalignment induces relativistic torques (the Lense–Thirring effect) on the disk, causing the disk to precess at early times, whereas at late times the disk aligns with the black hole and precession terminates. Here we report, using high-cadence X-ray monitoring observations of a tidal disruption event (TDE), the discovery of strong, quasi-periodic X-ray flux and temperature modulations. These X-ray modulations are separated by roughly 15days and persist for about 130days during the early phase of the TDE. Lense–Thirring precession of the accretion flow can produce this X-ray variability, but other physical mechanisms, such as the radiation-pressure instability, cannot be ruled out. Assuming typical TDE parameters, that is, a solar-like star with the resulting disk extending at most to the so-called circularization radius, and that the disk precesses as a rigid body, we constrain the disrupting dimensionless spin parameter of the black hole to be 0.05≤∣a∣≤0.5.

DOI: 10.1038/s41586-024-07433-w

Source: https://www.nature.com/articles/s41586-024-07433-w