Asymmetric Dark Matter May Alter the Evolution of Low-mass Stars and Brown Dwarfs

Abstract

We study energy transport by asymmetric dark matter in the interiors of very low-mass stars and brown dwarfs. Our motivation is to explore astrophysical signatures of asymmetric dark matter, which otherwise may not be amenable to conventional indirect dark matter searches. In viable models, the additional cooling of very-low mass stellar cores can alter stellar properties. Asymmetric dark matter with mass 4 < Mx/GeV < 10 and a spin-dependent (spin-independent) cross sections of sigma \sim 10^{-37} cm^2 (sigma \sim 10^{-40} cm^2) can increase the minimum mass of main sequence hydrogen burning, partly determining whether or not the object is a star at all. Similar dark matter candidates reduce the luminosities of low-mass stars and accelerate the cooling of brown dwarfs. Such light dark matter is of particular interest given results from the DAMA, CoGeNT, and CRESST dark matter searches. We discuss possibilities for observing dark matter effects in stars in the solar neighborhood, globular clusters, and, of particular promise, local dwarf galaxies, among other environments, as well as exploiting these effects to constrain dark matter properties.