Enhanced prospects for direct detection of inelastic dark matter from a non-galactic diffuse component

Abstract

In some scenarios, the dark matter particle predominantly scatters inelastically with the target, producing a heavier neutral particle in the final state. In this class of scenarios, the reach in parameter space of direct detection experiments is limited by the velocity of the dark matter particle, usually taken as the escape velocity from the Milky Way. On the other hand, it has been argued that a fraction of the dark matter particles in the Solar System could be bound to the envelope of the Local Group or to the Virgo Supercluster, and not to our Galaxy, and therefore could carry velocities larger than the escape velocity from the Milky Way. In this paper we estimate the enhancement in sensitivity of current direct detection experiments to inelastic dark matter scatterings with nucleons or electrons due to the non-galactic diffuse components, and we discuss the implications for some well motivated models.

Are there any extragalactic high speed dark matter particles in the Solar neighborhood?

“…We have used the APOSTLE suite of cosmological hydrodynamical simulations [20,21] to study the high-speed tail of the DM velocity distribution in the Solar neighborhood of MW-like halos. Our main goals are to characterize the tail of the distribution, to determine the origin of the maximum speeds achieved by DM particles, and to search for the presence of distinct components of high-speed DM particles of extragalactic origin hypothesized in earlier work [16][17][18][19].…”

“…Prior analytic work has suggested a further effect that may impact the highest velocities expected for DM particles in the Solar neighborhood, namely the possibility that "extragalactic" DM particles from the "envelopes" of the Local Group (LG) or the Virgo Supercluster may add a population of particles in a narrow range of velocities (about the MW local escape speed for the LG envelope, roughly 600 km/s, or exceeding 1000 km/s for the Virgo Supercluster) [16][17][18][19]. Such high speed DM particles in the Solar neighborhood can significantly impact the sensitivity of DM direct detection experiments [18,19].…”

Neutrino constraints on inelastic dark matter captured in the Sun

“…It is worth mentioning that other experiments like CRESST have enhanced sensitivity for larger mass splittings, and future heavy-nuclei based experiments can also probe a wider DM parameter space [48]. Moreover, the sensitivity of these experiments is also improved by accounting for an extra-galactic component in the DM velocity distribution [50]. However, systematic inclusion of this high-velocity component in WimPyDD as well as gravitational capture in the Sun (as discussed below) is beyond the scope of this work and left as a future effort.…”