Impact of nucleon-nucleon bremsstrahlung rates beyond one-pion exchange

Abstract

Neutrino-pair production and annihilation through nucleon-nucleon bremsstrahlung is included in current supernova simulations by rates that are based on the one-pion-exchange approximation. Here we explore the consequences of bremsstrahlung rates based on modern nuclear interactions for proto-neutron star cooling and the corresponding neutrino emission. We find that despite a reduction of the bremsstrahlung emission by a factor of 2--5 in the neutrinospheric region, models with the improved treatment exhibit only $\ensuremath{\lesssim}5%$ changes of the neutrino luminosities and an increase of $\ensuremath{\lesssim}0.7\text{ }\text{ }\mathrm{MeV}$ of the average energies of the radiated neutrino spectra, with the largest effects for the antineutrinos of all flavors and at late times. Overall, the proto-neutron star cooling evolution is slowed down modestly by $\ensuremath{\lesssim}0.5--1\text{ }\text{ }\mathrm{s}$.