Observing Lense-Thirring Precession in Tidal Disruption Flares

TL;DR

This paper investigates how Lense-Thirring precession around a rotating supermassive black hole affects the evolution of accretion disks formed after tidal disruption events, with implications for jet behavior and luminosity modulation.

Contribution

It demonstrates that Lense-Thirring precession causes significant time evolution of the disk's angular momentum, influencing observable features like jet precession and luminosity changes.

Findings

Lense-Thirring precession induces disk angular momentum evolution.

Jet precession and luminosity modulation are possible observational signatures.

Persistence of X-ray emission suggests jet alignment with SMBH spin axis.

Abstract

When a star is tidally disrupted by a supermassive black hole (SMBH), the streams of liberated gas form an accretion disk after their return to pericenter. We demonstrate that Lense-Thirring precession in the spacetime around a rotating SMBH can produce significant time evolution of the disk angular momentum vector, due to both the periodic precession of the disk and the nonperiodic, differential precession of the bound debris streams. Jet precession and periodic modulation of disk luminosity are possible consequences. The persistence of the jetted X-ray emission in the Swift J164449.3+573451 flare suggests that the jet axis was aligned with the spin axis of the SMBH during this event.