Quantifying uncertainties in the solar axion flux and their impact on determining axion model parameters

Abstract

We review the calculation of the solar axion flux from axion-photon and axionelectron interactions and discuss the size of various effects neglected in current calculations. For the Primakoff flux we then explicitly include the partial degeneracy of electrons. We survey the available solar models and opacity codes and develop a publicly available C++/Python code to quantify the associated systematic differences and statistical uncertainties. The number of axions emitted in helioseismological solar models is systematically larger by about 5% compared to photospheric models, while the overall statistical uncertainties in solar models are typically at the percent level in both helioseismological and photospheric models. However, for specific energies, the statistical fluctuations can reach up to about 5% as well. Taking these uncertainties into account, we investigate the ability of the upcoming helioscope IAXO to discriminate KSVZ axion models. Such a discrimination is possible for a number of models, and a discovery of KSVZ axions with high E/N ratios could potentially help to solve the solar abundance problem. We discuss limitations of the axion emission calculations and identify potential improvements, which would help to determine axion model parameters more accurately.

Revisiting axion-electron bremsstrahlung emission rates in astrophysical environments

“…( 5), the emissivity becomes ∼ 6% larger than the exact calculation, in agreement with Ref. [39]. However, the approximate expression in Eq.…”

“…The combination of these two effects gives a 1% discrepancy with respect to the exact calculation. Thus, our result is useful for an accurate characterization of the solar axion flux, which needs an high level of precision [39][40][41][42]. Furthermore, it permits to extend these studies to massive axions.…”

An introduction to axions and their detection

“…Once the existence of a non-zero g aγ is assumed, the prediction of this axion flux is very robust, as the solar interior is well-known. A recent study of the uncertainties [166] confirms a statistical uncertainty at the percent level, although the number of axions emitted in helioseismological solar models is systematically larger by about 5% compared to photospheric models. At energies below ∼keV the uncertainties are larger as other processes can contribute.…”

Probing the axion-nucleon coupling with the next generation of axion helioscopes

“…Helioscopes search primarily for axions originating from the Primakoff effect (cf, e.g. [52][53][54][55][56][57][58]) or from axion-electron interactions [22,[59][60][61]. This makes them sensitive to both the axion-photon coupling g aγ and to the product of photon and electron couplings g aγ g ae [22,62].…”

“…We use the solar axion flux library[60] which is publicly available at https://github.com/sebhoof/ SolarAxionFlux to perform all axion flux calculations.…”