Stellar Tidal Disruptions by Newborn Neutron Stars or Black Holes: A Mechanism for Hydrogen-poor (Super)luminous Supernovae and Fast Blue Optical Transients

Abstract Hydrogen-poor supernovae (SNe) of Type Ibc are explosions of massive stars that lost their hydrogen envelopes, typically due to interactions with a binary companion. We consider the case where the natal kick imparted to the neutron star (NS) or black hole (BH) remnant brings the compact object to a collision with a main-sequence companion, eventually leading to full tidal disruption of the companion. Subsequently, super-Eddington accretion onto the NS/BH launches a powerful, fast wind which collides with the SN ejecta and efficiently converts the kinetic energy of the wind into radiation. The radiation is reprocessed by the surrounding ejecta into a luminous (∼10 44 erg s −1 at peak), days to months-long transient with optical peaks from −19 to −21 mag, comparable to (super)luminous Type Ibc SNe and fast blue optical transients (FBOTs) such as AT2018cow. From a Monte Carlo analysis, we estimate the fraction of tidal disruptions following SNe in binaries to be ∼0.1%–1%, roughly compatible with the event rates of these luminous SNe. At the broad-brush level, our model reproduces the multiwavelength and spectral observations of FBOTs, and has the potential to explain peculiar features seen in some (super)luminous SNe that are difficult to reproduce by the conventional magnetar spin-down mechanism, such as late-time hydrogen lines, bumpy light curves, and prepeak excess.