Constraining asymmetric dark matter through observations of compact stars

We put constraints on asymmetric dark matter candidates with spin-dependent interactions based on the simple existence of white dwarfs and neutron stars in globular clusters. For a wide range of the parameters (WIMP mass and WIMP-nucleon cross section), weakly interacting massive particles (WIMPs) can be trapped in progenitors in large numbers and once the original star collapses to a white dwarf or a neutron star, these WIMPs might self-gravitate and eventually collapse forming a mini–black hole that eventually destroys the star. We impose constraints competitive to direct dark matter search experiments, for WIMPs with masses down to the TeV scale.

Figure 1

Constraints on the spin-dependent WIMP-proton cross section. The constraints follow from the existence of old white dwarfs in globular clusters [50] with a core dark matter density of ${10}^3\mathrm{GeV}/{\mathrm{cm}}^3$ (straight solid line) and ${10}^4\mathrm{GeV}/{\mathrm{cm}}^3$ (straight dashed line). We also show the constraints from direct searches (solid curve).

Figure 2

Constraints on the spin-dependent WIMP-nucleon cross section that follow from the existence of old neutron stars in globular clusters [52]. The grey area is excluded by direct accretion of WIMPs (for 10 Gyr) in an old neutron star with local dark matter density ${10}^3\mathrm{GeV}/{\mathrm{cm}}^3$. The purple area shows potential exclusion upon making an assumption regarding the distribution of WIMP velocities (see text), with the solid (dashed) line corresponding to local dark matter density ${10}^3({10}^4)\mathrm{GeV}/{\mathrm{cm}}^3$. We also show the exclusion area by direct dark matter search experiments.