Revisiting the axion bounds from the Galactic white dwarf luminosity function

It has been shown that the shape of the luminosity functionof white dwarfs(WDLF) is a powerful tool to check for the possible existence of DFSZ- axions, a proposed but not yet detected type of weakly interacting particles. With the aim of deriving new constraints on the axionmass, we compute in this paper new theoretical WDLFs on the basis of WD evolving models that incorporate the feedback of axionson the thermal structure of the white dwarf. We find that the impact of the axionemission into the neutrino emission can not be neglected at high luminosities M Bol 8) and that the axionemission needs to be incorporated self-consistently into the evolution of the white dwarfswhen dealing with axionmasses larger than ma cos 2β 5 meV (i.e. axion-electron coupling constant gae 1.4× 10-13). We went beyond previous works by including 5 different derivations of the WDLF in our analysis. Then we have performed χ2-tests to have a quantitative measure of the agreement between the theoretical WDLFs — computed under the assumptions of different axionmasses and normalization methods --- and the observed WDLFs of the Galactic disk. While all the WDLF studied in this work disfavour axionmasses in the range suggested by asteroseismologyma cos 2β 10 meV; gae 2.8× 10-13) lower axionmasses can not be discarded from our current knowledge of the WDLF of the Galactic Disk. A larger set of completely independent derivations of the WDLF of the galactic disk as well as a detailed study of the uncertainties of the theoretical WDLFs is needed before quantitative constraints on the axion-electron coupling constant can be made.