The diffuse supernova neutrino background: an update with modern population synthesis and core-collapse simulations

TL;DR

This paper provides an updated, comprehensive calculation of the diffuse supernova neutrino background using advanced simulations and population synthesis, accounting for binary evolution and black hole formation effects.

Contribution

It introduces a novel methodology combining multi-dimensional supernova simulations with population synthesis to model the DSNB more accurately.

Findings

Black hole-forming collapses can increase the DSNB by up to 50% at high energies.

Binary evolution effects can alter the total collapse rate and produce stronger neutrino emitters.

Overall, the net increase in DSNB flux due to these effects is up to 15%.

Abstract

We present a new, state-of-the-art computation of the Diffuse Supernova Neutrino Background (DSNB), where we use neutrino spectra from multi-dimensional, multi-second core collapse supernova simulations - including both neutron-star and black-hole forming collapses - and binary evolution effects from modern population synthesis codes. Large sets of numerical results are processed and connected in a consistent manner, using two key quantities: the mass of the star's Carbon-Oxygen (CO) core at an advanced pre-collapse stage - which depends on binary evolution effects - and the compactness parameter, which is the main descriptor of the post-collapse neutrino emission. The method enables us to model the neutrino emission of a very diverse, binary-affected population of stars, which cannot unambiguously be mapped in detail by existing core collapse simulations. We find that including black hole-forming collapses enhances the DSNB by up to 50% at energies greater than 30-40 MeV. Binary evolution effects can change the total rate of collapses and generate a sub-population of high core mass stars that are stronger neutrino emitters. However, the net effect on the DSNB is moderate - up to a 15% increase in flux - due to the rarity of these super-massive cores and to the relatively modest dependence of the neutrino emission on the CO core mass. The methodology presented here is suitable for extensions and generalizations, and therefore it lays the foundation for modern treatments of the DSNB.