  Tidal disruption events (TDEs) taking place in active galactic nuclei (AGNs)
are different from ordinary TDEs. In these events, the returning tidal debris
stream drills through the pre-existing AGN accretion disk near the stream
pericenter, destroying the inner disk in the process, and then intersects with
the disk a second time at radii ranging from a few to hundreds of times the
pericenter distance. The debris dynamics of such TDEs, and hence their
appearance, are distinct from ordinary TDEs. Here we explore the signature of
this "second impact" of the stream with the disk. Strong shocks form as the
dilute stream is stopped by the denser disk. Compton cooling of the shocked
material produces hard X-rays, even soft gamma-rays, with most of the energy
emitted between ~10 keV and 1 MeV. The luminosity follows the mass-return rate,
peaking between ~$10^{42}$ and $10^{44}$ erg/s. The X-ray hardness and the
smoothness of the light curve provide possible means for distinguishing the
second impact from ordinary AGN flares, which exhibit softer spectra and more
irregular light curves.
