Ultra-Close Encounters of Stars With Massive Black Holes: Tidal
  Disruption Events With Prompt Hyperaccretion
  A bright flare from a galactic nucleus followed at late times by a $t^{-5/3}$
decay in luminosity is often considered the signature of the complete tidal
disruption of a star by a massive black hole. The flare and power-law decay are
produced when the stream of bound debris returns to the black hole,
self-intersects, and eventually forms an accretion disk or torus. In the
canonical scenario of a solar-type star disrupted by a $10^{6}\; M_\odot$ black
hole, the time between the disruption of the star and the formation of the
accretion torus could be years. We present fully general relativistic
simulations of a new class of tidal disruption events involving ultra-close
encounters of solar-type stars with intermediate mass black holes. In these
encounters, a thick disk forms promptly after disruption, on timescales of
hours. After a brief initial flare, the accretion rate remains steady and
highly super-Eddington for a few days at $\sim 10^2\,M_\odot\,{\rm yr}^{-1}$.
