The Eccentric Nature of Eccentric Tidal Disruption Events
  Upon entering the tidal sphere of a supermassive black hole, a star is ripped
apart by tides and transformed into a stream of debris. The ultimate fate of
that debris, and the properties of the bright flare that is produced and
observed, depends on a number of parameters, including the energy of the center
of mass of the original star. Here we present the results of a set of smoothed
particle hydrodynamics simulations in which a $1~M_\odot $, $\gamma = 5/3$
polytrope is disrupted by a $10^6 ~M_\odot$ supermassive black hole. Each
simulation has a pericenter distance of $r_{\rm p} = r_{\rm t}$ (i.e., $\beta
\equiv r_{\rm t}/r_{\rm p} = 1$ with $r_{\rm t}$ the tidal radius), and we vary
the eccentricity $e$ of the stellar orbit from $e = 0.8$ up to $e = 1.20$ and
study the nature of the fallback of debris onto the black hole and the
long-term fate of the unbound material. For simulations with eccentricities $e
\lesssim 0.98$, the fallback curve has a distinct, three-peak structure that is
induced by self-gravity. For simulations with eccentricities $e \gtrsim 1.06$,
the core of the disrupted star reforms following its initial disruption. Our
results have implications for, e.g., tidal disruption events produced by
supermassive black hole binaries.
