Nuclear neutrino energy spectra in high temperature astrophysical environments

TL;DR

This paper investigates nuclear neutrino energy spectra in high-temperature astrophysical environments, emphasizing the importance of nuclear structure and transitions in accurately predicting neutrino emissions.

Contribution

It highlights the significance of nuclear processes and detailed nuclear structure in modeling neutrino spectra, challenging simplified single-transition approaches.

Findings

Nuclear processes produce the highest-energy neutrinos in hot astrophysical environments.

Excited nuclear states can significantly influence the neutrino spectrum.

Simplified models may miss important spectral features due to neglecting nuclear structure.

Abstract

Astrophysical environments that reach temperatures greater than $\sim$ 100 keV can have significant neutrino energy loss via both plasma processes and nuclear weak interactions. We find that nuclear processes likely produce the highest-energy neutrinos. Among the important weak nuclear interactions are both charged current channels (electron capture/emission and positron capture/emission) and neutral current channels (de-excitation of nuclei via neutrino pair emission). We show that in order to make a realistic prediction of the nuclear neutrino spectrum, one must take nuclear structure into account; in some cases, the most important transitions may involve excited states, possibly in both parent and daughter nuclei. We find that the standard technique of producing a neutrino energy spectrum by using a single transition with a Q-value and matrix element chosen to fit published neutrino production rates and energy losses will not accurately capture important spectral features.