Spectra of axions emitted from main sequence stars

TL;DR

This paper calculates the energy spectra of axions emitted by main sequence stars, estimating the diffuse axion background in the universe and discussing its distinguishability from other sources.

Contribution

It provides detailed stellar axion spectra based on stellar models and estimates the diffuse axion background from all stars, a novel comprehensive analysis.

Findings

Stellar axion spectra are computed across a range of stellar masses.

The diffuse axion background from stars is quantified and characterized.

Stellar axion fluxes are distinguishable from solar and early universe sources.

Abstract

We compute the detailed energy spectra of axions with two-photon coupling produced in stellar cores over a wide range of stellar masses. We focus on main sequence stars and base our calculations on the stellar interior profiles from MESA, for which we provide simple fits in an appendix. The obtained stellar axion spectra, combined with recent models of star formation history and stellar initial mass function, enable us to estimate the properties of the diffuse axion background sourced by all the stars in the universe. The fluxes of this stellar axion background and its decay photons are subdominant to but can in principle be disentangled from those expected from the Sun and the early universe based on their different spectral and spatial profiles.