  The most luminous Supernova SN2006gy (more than a 100 times brighter than a
typical supernova) has been a challenge to explain by standard models. For
example, pair instability supernovae which are luminous enough seem to have too
slow a rise, and core collapse supernovae do not seem to be luminous enough. We
present an alternative scenario involving the quark-nova phenomenon (an
explosive transition of the newly born neutron star to a quark star) in which a
second explosion (delayed) occurs inside the ejecta of a normal supernova. The
reheated supernova ejecta can radiate at higher levels for longer periods of
time primarily due to reduced adiabatic expansion losses, unlike the standard
supernova case. We find an encouraging match between the resulting lightcurve
and that observed in the case of SN2006gy suggesting that we might have at hand
the first ever signature of a quark-nova. Successful application of our model
to SN2005gj and SN2005ap is also presented.
