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^1,2. 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 15 days and persist for about 130 days 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^3,4, 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.

超大质量黑洞扰乱恒星后在其周围形成的吸积盘预计最初会相对于黑洞的赤道面错位。这种错位会在圆盘上产生相对论扭矩（透镜-蒂林效应），导致圆盘在早期进动，而在晚期，圆盘与黑洞对齐并且进动终止 ^1,2 。在此，我们报告利用潮汐破坏事件 (TDE) 的高频率 X 射线监测观测，发现了强的准周期性 X 射线通量和温度调制。这些 X 射线调制间隔大约 15 天，并在 TDE 的早期持续大约 130 天。吸积流的透镜-蒂林进动可以产生这种 X 射线变化，但不能排除其他物理机制，例如辐射压力不稳定性 ^3,4 。假设典型的 TDE 参数，即一颗类太阳恒星，其形成的圆盘最多延伸到所谓的圆化半径，并且该圆盘作为刚体进动，我们将黑洞的破坏性无量纲自旋参数限制为为 0.05 ≲ ∣a∣ ≲ 0.5。