Mass ejection in failed supernovae: equation of state and neutrino loss dependence

TL;DR

This study investigates how the nuclear equation of state and neutrino losses influence mass ejection in failed supernovae, revealing significant variations in ejecta mass and energy based on these factors, with implications for observable transients.

Contribution

It provides a detailed, self-consistent simulation of core-collapse and mass ejection in failed supernovae, highlighting the impact of the equation of state and neutrino loss modeling on outcomes.

Findings

EOS affects neutrino mass loss by a factor of two.

Soft EOS results in lower ejecta mass and energy.

Neutrino loss history approximations are within 10% of detailed models.

Abstract

A failed core-collapse supernova from a non-rotating progenitor can eject mass due to a weakening of gravity associated to neutrino emission by the protoneutron star. This mechanism yields observable transients and sets an upper limit to the mass of the black hole (BH) remnant. Previous global simulations of this mechanism have included neutrino losses parametrically, however, with direct implications for the ejecta mass and energy. Here we evolve the inner supernova core with a spherically-symmetric, general-relativistic neutrino radiation-hydrodynamic code until BH formation. We then use the result in a Newtonian code that follows the response of the outer layers of the star to the change in gravity and resolves the surface pressure scale height. We find that the dense-matter equation of state (EOS) can introduce a factor $\sim 2$ variation in gravitational mass lost to neutrinos, with a stiff EOS matching previous parametric results, and a soft EOS yielding lower ejecta masses and energies by a factor of several. This difference is caused primarily by the longer time to BH formation in stiffer EOSs. With a soft EOS, our red and yellow supergiant progenitors fail to unbind mass if hydrogen recombination energy is not included. Using a linear ramp in time for mass-energy lost to neutrinos (with suitable parameters) yields a stellar response within $\sim 10\%$ of that obtained using the detailed history of neutrino losses. Our results imply quantitative but not qualitative modifications to previous predictions for shock breakout, plateau emission, and final BH masses from these events.