High-resolution supernova neutrino spectra represented by a simple fit

TL;DR

This paper demonstrates that supernova neutrino spectra can be accurately represented by a simple quasi-thermal fit, enabling effective predictions of detector responses based on key spectral parameters.

Contribution

The study shows that a simple fit using mean and RMS energies accurately models supernova neutrino spectra, improving detector response predictions.

Findings

Spectra are well represented by the fit at various post-bounce times.

The fit reproduces detector counting rates across different target nuclei.

Mean and RMS energies suffice to determine spectral shape and detector response.

Abstract

To study the capabilities of supernova neutrino detectors, the instantaneous spectra are often represented by a quasi-thermal distribution of the form f(E) = E^alpha e^{-(alpha+1)E/E_{av}} where E_{av} is the average energy and alpha a numerical parameter. Based on a spherically symmetric supernova model with full Boltzmann neutrino transport we have, at a few representative post-bounce times, re-converged the models with vastly increased energy resolution to test the fit quality. For our examples, the spectra are well represented by such a fit in the sense that the counting rates for a broad range of target nuclei, sensitive to different parts of the spectrum, are reproduced very well. Therefore, the mean energy and root-mean-square energy of numerical spectra hold enough information to provide the correct alpha and to forecast the response of multi-channel supernova neutrino detection.