In the absence of high-statistics supernova neutrino measurements, estimates
of the diffuse supernova neutrino background (DSNB) hinge on the precision of
simulations of core-collapse supernovae (CCSNe). Understanding the cooling
phase of protoneutron star (PNS) evolution (≳1s after core
bounce) is crucial, since approximately 50% of the energy liberated by
neutrinos is emitted during the cooling phase. We model the cooling phase with
a hybrid method, by combining the neutrino emission predicted by 3D
hydrodynamic simulations with several cooling phase estimates, including a
novel two-parameter correlation depending on the final baryonic PNS mass and
the time of shock revival. We find that the predicted DSNB event rate at
Super-Kamiokande can vary by a factor of ∼2−3 depending on the cooling
phase treatment. We also find that except for one cooling estimate, the range
in predicted DSNB events is largely driven by the uncertainty in the neutrino
mean energy. With a good understanding of the late time neutrino emission, more
precise DSNB estimates can be made for the next generation of DSNB searches.Comment: 13 pages, 6+4 figures, 5 tables. Comments welcom