Superluminous Supernovae SN2006gy, SN2005gj and SN2005ap: Signs for a New Explosion Mechanism

upernova SN2006gy was far brighter than a typical supernova) and has challenged explanations by standard models. Pair instability supernovae seem to be luminous enough but have too slow a rise, whereas core collapse supernovae rise rapidly enough but do not seem to be luminous enough. Similarly, other superluminous supernovae, SN2005gj and SN2006ap, also provide challenges to standard models. This work has two parts. It is shown that the lightcurve of SN2006gy is consistent with shock radiation from an explosion in a very extended envelope, where the large size alleviates the adiabatic expansion loss problem. Then a scenario is presented to obtain an explosion in an extended envelope. The envelope is produced by a normal massive star explosion, which is then energized by the explosive transition of the neutron star to a quark star. This second explosion is delayed so that it occurs inside the extended ejecta of the first normal (and fainter) supernova. The resulting lightcurve is calculated in this double explosion model and it gives a good match to the observed lightcurves of SN2006gy, Sn2005gj and SN2005ap. The results suggest that we might have at hand the first ever signature of explosive conversion of a neutron star into a quark star.