Spectra and rates of bremsstrahlung neutrino emission in stars

TL;DR

This paper calculates detailed neutrino emission rates from electron-nucleus bremsstrahlung in stars, considering screening effects, and compares these with other neutrino production processes across various stellar conditions.

Contribution

It provides updated energy loss rates for neutrino emission processes in stars, incorporating screening and correlations, and identifies dominant processes in different stellar regimes.

Findings

Bremsstrahlung neutrino emission rates are quantified with screening effects.

Pair annihilation dominates the neutrino signal in pre-supernova stars.

Updated rates improve modeling of stellar evolution and neutrino detection.

Abstract

We calculate the energy-differential rate for neutrino emission from electron-nucleus bremsstrahlung in stellar interiors taking into account the effects of electron screening and ionic correlations. We compare the energy-differential and the net rates, as well as the average $\bar{\nu}_e$ and $\bar{\nu}_x$ $(x = {\mu}, {\tau})$ energies, for this process with those for $e^{\pm}$ pair annihilation, plasmon decay, and photo-neutrino emission over a wide range of temperature and density. We also compare our updated energy loss rates for the above thermal neutrino emission processes with the fitting formulas widely used in stellar evolution models and determine the temperature and density domain in which each process dominates. We discuss the implications of our results for detection of $\bar{\nu}_e$ from massive stars during their pre-supernova evolution and find that pair annihilation makes the predominant contribution to the signal from the thermal emission processes.