What happens if a star orbits very close to a supermassive black hole in a galactic center? If the star approaches within tens of times the event horizon of the black hole, the black holes’s intense tidal forces would tear the star apart in a matter of hours, generating a luminous flare, known as a tidal disruption event (TDE). Since the first detection in the 1990s, the number of detected events has steadily increased thanks to ongoing time-domain surveys and telescopes, such as ZTF, ASAS-SN, and Pan-STARRS, now totaling several hundred. With the Vera C. Rubin Observatory, detection rates are expected to rise by several orders of magnitude over the coming decade. In this exciting time-domain era, reliably identifying TDEs and interpreting this rapidly expanding sample will be crucial, requiring a clear understanding of the dominant emission mechanism near peak luminosity, typically about a month after disruption. The standard paradigm assumes that the stellar debris rapidly circularizes into an accretion disk, and that the observed radiation is powered by accretion. However, is this assumption valid? In this talk, I will present fully relativistic hydrodynamics simulations with realistic stellar structure that challenge this picture. Our results indicate that debris circularization in TDEs may be intrinsically slow and shocks are what powers the events, with important implications for interpreting early-time flares.
