Probing the dark matter velocity distribution via daily modulation

Abstract

We consider dark matter velocity distributions with an anisotropic component, and analyze how the velocity structure can be probed in a solid state ionization detector with no directional detection capability using a daily modulation effect due to the anisotropic response function of the target. We show that with an energy resolution of < 10 eV it is possible to identify the presence of an anisotropic component consistent with observations for sub-GeV dark matter, and that introduction of daily modulation information substantially improves the sensitivity in a narrow mass range.