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

Abstract

We present synthetic light curves of fallback-powered supernovae based on a neutrino-driven explosion of a 40 M ⊙ 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.

Supernova Fallback as Origin of Neutron Star Spins and Spin-kick Alignment

“…In massive progenitors with high densities in their collapsing cores and high mass accretion rates of the new-born neutron stars, the hydrody-namic kicks typically dominate the neutrino-induced kicks (see Bollig et al 2020), whereas in low-mass progenitors with low mass accretion rates the neutrino-induced kicks can provide the leading contribution (see Stockinger et al 2020). The kick velocities obtained in the simulations are viable to explain the space velocities of young neutron stars and radio pulsars inferred from observations (see, e.g., Lyne & Lorimer 1994;Lorimer et al 1997;Cordes & Chernoff 1998;Arzoumanian et al 2002) Fallback in supernovae has previously been considered as a source of post-explosion emission of electromagnetic radiation (Chevalier 1989) and neutrinos (Houck & Chevalier 1991;Chevalier 1995), as an origin of disk formation around neutron stars and black holes in successful and failed supernovae and of associated light emission (Dexter & Kasen 2013;Perna et al 2014;Quataert et al 2019;Moriya et al 2018Moriya et al , 2019, as kick mechanism of black holes (Janka 2013;Chan et al 2020), as a possible production site of r-process elements (Fryer 2006;Fryer et al 2006), and as a mechanism of magnetic field amplification in the surface layers of the new-born neutron star (Soker 2020). However, to our best knowledge, the dynamics of anisotropic fallback and its dependence on the neutron star kick in an asymmetric supernova explosion have not been discussed before.…”

The electron-capture origin of supernova 2018zd

“…For such high fallback accretion, however, extra luminosity (L ∝ t −5/3 ) at late times (t 200 d) is expected 122,123 . Also, no ejected stable 58 Ni should be observed, as produced in the innermost neutron-rich layer 10 .…”

DES16C3cje: A low-luminosity, long-lived supernova

“…While the late-time light curve of DES16C3cje is following a decline rate close to −5/3 , we cannot rule out a scenario involving interaction with CSM. Moriya et al (2019) briefly discuss the possibility of CSM interaction in fallback SN and the need to study this issue in the future.…”

“…Larger accretion rates produce more luminous light curves and earlier plateaus than observed. In addition, a delayed deposition of the fallback energy is not a solution as despite the low accretion rate, a time delay factor produces an extremely luminous plateau (similar to figure 2 of Moriya et al 2019) and a brighter light curve tail.…”