Fallback Accretion-powered Supernova Light Curves Based on a Neutrino-driven Explosion Simulation of a 40 M⊙ Star

Abstract We present synthetic light curves (LCs) of fallback-powered supernovae based on a neutrino-driven explosion of a 40 zero-metallicity star with significant fallback accretion onto a black hole that was previously simulated by Chan et al. until shock breakout. Here, we investigate the LC properties of the explosion after shock breakout for various fallback models. Without extra power from fallback accretion, the LC is that of an SN IIP with a plateau magnitude of around −14 mag and a plateau duration of 40 days. With extra power for the LC from fallback accretion, however, we find that the transient can be significantly more luminous. The LC shape can be SN 1987A-like or Type IIP-like, depending on the efficiency of the fallback engine. If the accretion disk forms soon after the collapse and more than 1% of the accretion energy is released as the central engine, fallback accretion-powered supernovae become as luminous as superluminous supernovae. We suggest that Type II superluminous supernovae with broad hydrogen features could be related to such hydrogen-rich supernovae powered by fallback accretion. In the future, such superluminous supernovae powered by fallback accretion might be found among the supernovae from the first stars in addition to pair-instability supernovae and pulsational pair-instability supernovae.