2021/07/07 by Ilídio Lopes
Physics and Astronomy · #Astronomy #Astrophysics #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #Ion #Mass spectrum #Physics #Spectral line #Stars #astro-ph.CO #astro-ph.HE #astro-ph.SR #hep-ph
paper · pdf · doi:10.1103/physrevd.104.023008
published as Physical Review D, Volume 104, Issue 2, article id.023008 (2021) · 12 pages, 1 table, 4 figures, published in PRD
openalex publication_date 2021/07/07 · arxiv created 2021/07/29 · arxiv updated 2021/08/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Axion particles are among the best candidates to explain dark matter and resolve the strong CP problem in the Standard Model. If such a particle exists, the core of stars will produce them in large amounts. For the first time, we predict the axion spectra and their associated luminosities for several low-mass stars---one and two solar masses stars in the main sequence and post-main sequence stages of evolution. Equally, we also compute the x-ray excess emission resulting from the conversion of axions back to photons in the presence of a strong magnetic field in the envelope of these stars. Hence, a given star will have a unique axion spectrum and La axion luminosity. And if such star has a strong magnetic field in its stellar envelope, it will also show a characteristic x-ray spectrum and L_a\ensuremathγ x-ray luminosity. Such radiation will add up to the x-ray electromagnetic spectrum and LX luminosity of the star. The present study focuses on axion models with an axion-photon coupling constant, 5 10^\ensuremath-11 GeV^\ensuremath-1, a value just below the most recent upper limit of 6.6 10^\ensuremath-11 GeV^\ensuremath-1 found by CAST and IAXO helioscopes. The range of axion parameters discussed here spans many axion models' parameter space, including the DFSZ and KSVZ models. We found that axions with a mass in the range 10^\ensuremath-7 to 10^\ensuremath-5 eV and an axion-photon coupling constant of 5 10^\ensuremath-11 GeV^\ensuremath-1 produce an axion emission spectra with an averaged axion energy that varies from 1 to 5 KeV, and an La ranging from 10^\ensuremath-6 to 7 10^\ensuremath-3L_\ensuremath\bigodot. We also predict that L_a\ensuremathγ varies from 5 10^\ensuremath-8 to 10^\ensuremath-5L_\ensuremath\bigodot for stars with an averaged magnetic field of 3104 G in their atmospheres. Most of these L_a\ensuremathγ predictions are larger than the LX observed in some stars. Therefore, such preliminary results show the potential of the next generation of stellar x-ray missions to constrain several classes of axion models.