Bracketing the impact of astrophysical uncertainties on local dark matter searches

Abstract

The theoretical interpretation of dark matter (DM) experiments is hindered by\nuncertainties on the dark matter density and velocity distribution inside the\nSolar System. In order to quantify those uncertainties, we present a parameter\nthat characterizes the deviation of the true velocity distribution from the\nstandard Maxwell-Boltzmann form, and we then determine for different values of\nthis parameter the most aggressive and most conservative limits on the dark\nmatter scattering cross section with nuclei; uncertainties in the local dark\nmatter density can be accounted for trivially. This allows us to bracket, in a\nmodel independent way, the impact of astrophysical uncertainties on limits from\ndirect detection experiments and/or neutrino telescopes. We find that current\nlimits assuming the Standard Halo Model are at most a factor of $\\sim 2$ weaker\nthan the most aggressive possible constraints. In addition, combining neutrino\ntelescope and direct detection constraints (in a statistically meaningful way),\nwe show that limits on DM in the mass range $\\sim 10 - 1000$ GeV cannot be\nweakened by more than around a factor of 10, for all possible velocity\ndistributions. We finally demonstrate that our approach can also be employed in\nthe event of a DM discovery, allowing us to avoid bias in the reconstruction of\nthe DM properties.\n