Lense-Thirring precession around supermassive black holes during tidal disruption events
Abstract
A tidal disruption event (TDE) occurs when a star wanders close enough to a black hole to be disrupted by its tidal force. The debris of a tidally disrupted star are expected to form an accretion disc around the supermassive black hole. The light curves of these events sometimes show a quasi-periodic modulation of the flux that can be associated with the precession of the accretion disc due to the Lense-Thirring ("frame-dragging") effect. Since the initial star orbit is in general inclined with respect to the black hole spin, this misalignment combined with the Lense-Thirring effect leads to a warp in the disc. In this paper we provide a simple model of the system composed by a thick and narrow accretion disc surrounding a spinning supermassive black hole, with the aim to: (a) compute the expected precession period as a function of the system parameters, (b) discuss the conditions that have to be satisfied in order to have rigid precession, (c) investigate the alignment process, highlighting how different mechanisms play a role leading the disc and the black hole angular momenta into alignment.
Keywords
Cite
@article{arxiv.1510.04879,
title = {Lense-Thirring precession around supermassive black holes during tidal disruption events},
author = {A. Franchini and G. Lodato and S. Facchini},
journal= {arXiv preprint arXiv:1510.04879},
year = {2015}
}
Comments
Accepted for publication in MNRAS, 12 pages, 12 figures