Asteroseismology: Looking for axions in the red supergiant star Alpha Ori

TL;DR

This study uses seismic data and surface abundances of the red supergiant Alpha Ori to set upper bounds on axion-photon coupling, revealing potential effects of axions on stellar structure and evolution.

Contribution

First application of seismic data to constrain axion-photon coupling in a supergiant star, establishing upper limits and identifying observable effects of axion energy losses.

Findings

Models with $g_{a ext{γ}}$ up to 2.0×10^{-10} GeV^{-1} fit observations

Higher $g_{a ext{γ}}$ values lead to incompatible stellar models

Axion energy losses cause measurable luminosity and neutrino production increases

Abstract

In this work, for the first time, we use seismic data as well as surface abundances to model the supergiant $\alpha$-Ori, with the goal of setting an upper bound on the axion-photon coupling constant $g_{a\gamma}$. We found that, in general, the stellar models with $g_{a \gamma} \in [0.002;2.0]\times 10^{-10}{\rm GeV}^{-1}$ agree with observational data, but beyond that upper limit, we did not find stellar models compatible with the observational constraints, and current literature. From $g_{a \gamma} = 3.5 \times 10^{-10} {\rm GeV}^{-1}$ on, the algorithm did not find any fitting model. Nevertheless, all axionic models considered, presented a distinct internal profile from the reference case, without axions. Moreover, as axion energy losses become more significant, the behaviour of the stellar models becomes more diversified, even with very similar input parameters. Nonetheless, the consecutive increments of $g_{a \gamma}$ still show systematic tendencies, resulting from the axion energy losses. Moreover, we establish three important conclusions: (1) The increased luminosity and higher neutrino production are measurable effects, possibly associated with axion energy losses. (2) Stellar models with axion energy loss show a quite distinct internal structure. (3) The importance of future asteroseismic missions in observing low-degree non-radial modes in massive stars:internal gravity waves probe the near-core regions, where axion effects are most intense. Thus, more seismic data will allow us to constrain $g_{a\gamma}$ better and prove or dismiss the existence of axion energy loss inside massive stars.