First axion bounds from a pulsating helium-rich white dwarf star

BATTICH, T.; CÓRSICO, A. H.; ALTHAUS, L. G.; MILLER BERTOLAMI, M. M.

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS

IOP PUBLISHING LTD

Lugar: Londres; Año: 2016

1475-7516

The Peccei-Quinn mechanism proposed to solve the CP problem of QuantumChromodynamics has as consequence the existence of axions, hypotheticalweakly interacting particles whose mass is constrained to be on thesub-eV range. If these particles exist and interact with electrons, theywould be emitted from the dense interior of white dwarfs, becoming animportant energy sink for the star. Due to their well known physics,white dwarfs are good laboratories to study the properties offundamental particles such as the axions. We study the general effect ofaxion emission on the evolution of helium-rich white dwarfs and on theirpulsational properties. To this aim, we calculate evolutionaryhelium-rich white dwarf models with axion emission, and assess thepulsational properties of this models. Our results indicate that therates of change of pulsation periods are significantly affected by theexistence of axions. We are able for the first time to independentlyconstrain the mass of the axion from the study of pulsating helium-richwhite dwarfs. To do this, we use an estimation of the rate of change ofperiod of the pulsating white dwarf PG 1351+489 corresponding to thedominant pulsation period. From an asteroseismological model of PG1351+489 we obtain gae < 3.3 ×10‑13 for the axion-electron coupling constant, ormacos2β lesssim 11.5 meV for the axion mass.This constraint is relaxed to gae < 5.5 ×10‑13 (macos2β lesssim 19.5meV), when no detailed asteroseismological model is adopted for thecomparison with observations.