Extremely Relativistic Tidal Disruption Events

TL;DR

Extreme tidal disruption events (eTDEs) occur when stars pass very close to supermassive black holes, producing distinctive relativistic signatures observable through their unique debris dynamics and emission patterns.

Contribution

This study introduces the first detailed general relativistic hydrodynamics simulations of eTDEs, revealing their unique debris evolution and observational features distinct from ordinary TDEs.

Findings

eTDEs produce rapid, luminous X-ray emissions lasting weeks to a year.

Debris forms tight spirals and ejects some mass, powering observable signals.

Most eTDEs occur around higher-mass black holes, offering new relativistic phenomena insights.

Abstract

Extreme tidal disruption events (eTDEs), which occur when a star passes very close to a supermassive black hole, may provide a way to observe a long-sought general relativistic effect: orbits that wind several times around a black hole and then leave. Through general relativistic hydrodynamics simulations, we show that such eTDEs are easily distinguished from most tidal disruptions, in which stars come close, but not so close, to the black hole. Following the stellar orbit, the debris in eTDEs is initially distributed in a crescent that quickly turns into tight spirals, from which some mass later falls back toward the black hole, while the remainder is ejected. Internal shocks within the infalling debris power the observed emission. The resulting light-curve rises rapidly to roughly the Eddington luminosity, maintains this level for between a few weeks and a year (depending on both the stellar mass and the black hole mass), and then drops. Most of its power is in thermal X-rays at a temperature $\sim (1-2)\times 10^{6}$ K ($\sim 100-200$ eV). The debris evolution and observational features of eTDEs are qualitatively different from ordinary TDEs, making eTDEs a new type of TDE. Although eTDEs are relatively rare for lower-mass black holes, most tidal disruptions around higher-mass black holes are extreme. Their detection offers a view of an exotic relativistic phenomenon previously inaccessible.