Paper

Lense-Thirring Precession after a Supermassive Black Hole Disrupts a Star

Guolo, Muryel, Sniegowska, Marzena, Yukta Ajay, Zajacek, Michal, Janiuk, Agnieszka, Pasham, Dheeraj R, Coughlin, Eric R, Loewenstein, Michael, Wevers, Thomas, Nixon, C J, Czerny, Bozena

2024

Overview

An accretion disk formed around a supermassive black hole (SMBH) after it disrupts a star is expected to be initially misaligned with respect to the black hole's equatorial plane. This misalignment induces relativistic torques (the Lense-Thirring effect) on the disk, causing the disk to precess at early times, while at late times the disk aligns with the black hole and precession terminates. Here, using high-cadence X-ray monitoring observations of a TDE, we report the discovery of strong, quasi-periodic X-ray flux and temperature modulations from a TDE. These X-ray modulations are separated by 17.0\\(^+1.2_-2.4\\) days and persist for roughly 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, cannot be ruled out. Assuming typical TDE parameters, i.e., a solar-like star with the resulting disk extending at-most to so-called circularization radius, and that the disk precesses as a rigid body, we constrain the disrupting black hole's dimensionless spin parameter to be 0.05<|a|<0.5.

• Publisher: Cornell University Library, arXiv.org
• Subject: Accretion disks / Misalignment / Parameters / Precession / Rigid structures / Supermassive black holes