  We present synthetic light curves of fallback-powered supernovae based on a
neutrino-driven explosion of a 40 Msun zero-metallicity star with significant
fallback accretion onto a black hole that was previously simulated by Chan et
al. (2018) until shock breakout. Here, we investigate the light curve
properties of the explosion after shock breakout for various fallback models.
Without extra power from fallback accretion, the light curve is that of a Type
IIP supernova with a plateau magnitude of around -14 mag and a plateau duration
of 40 days. With extra power for the light curve from fallback accretion,
however, we find that the transient can be significantly more luminous. The
light-curve 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 pulstational
pair-instability supernovae.
