Tidal Disruption Events

A rare glimpse into the properties of a normally quiescent supermassive black hole is afforded when a star passes sufficiently close that it is torn apart by the black hole’s tidal gravitational field. Most of such tidal disruption events (TDEs) result in a `flare' at optical, UV, and X-ray wavelengths that lasts from months to years and is thought to be powered by the gas falling into the supermassive black hole (SMBH). Recently me and Zack Andalman for the first time simulated in GRHD a solar mass star on a realistic parabolic orbit that got tidally disrupted by a million solar mass SMBH. The extreme mass ratio between star and SMBH makes the stream very thin and challenging to resolve numerically. We showed (see video below) that a pericenter shock is the dominant mechanism in forming an accretion disk from a TDE stream and for the first time demonstrated that periodic self-intersections of the accretion stream can be so violent that they totally disrupt the stream and may explain flaring detected by NASA's Swift satellite in the light curve of TDE J1644+57.

The video below shows a similar simulation, but where the TDE stream and accretion disk are misaligned. The similarities and differences between aligned and misaligned models are described in our paper.

In the near future our collaboration is moving towards radiative GRMHD simulations that will evolve the TDEs for much longer timescales. This will allow us to quantify the effects of radiative outflows and to make more accurate observational predictions for TDEs.

Publications

1) Tidal Disruption Disks Formed and Fed by Stream-Stream and Stream-Disk Interactions in Global GRHD Simulations