Halo uncertainties in electron recoil events at direct detection experiments

Abstract

The dark matter direct detection rates are highly correlated with the phase space distribution of dark matter particles in our galactic neighbourhood. In this paper we make a systematic study of the impact of astrophysical uncertainties on electron recoil events at the direct detection experiments with Xenon and semiconductor detectors. We find that within the standard halo model there can be up to $$ \sim 50\%$$ ∼ 50 % deviation from the fiducial choice in the exclusion bounds from these observational uncertainties. For non-standard halo models we report a similar deviation from the fiducial standard halo model when fitted with recent cosmological N-body simulations while even larger deviations are obtained in case of the observational uncertainties.

Dark matter substructures affect dark matter-electron scattering in xenon-based direct detection experiments

“…The DM velocity required to have a measurable recoil is rather high, which can be found near the tail of the DM velocity distribution (assuming that it has a Maxwell-Boltzmann form). These tails are quite sensitive to the choice of the DM velocity distribution [72][73][74][75]. The present DM velocity distribution depends on the galactic structure formation history.…”

“…It was shown in ref. [75] that the effect of such astrophysical uncertainties is quite prominent for xenon targets. Further, in large regions of the DM parameter space, the sensitivity of xenon targets is a few orders of magnitude stronger than those from semiconductor-based experiments [63,[69][70][71] implying that xenon detectors will probably play a big role in discovering DM-electron scattering.…”

“…Following refs. [75,156], throughout the paper we fix v 0 = 233 km/s. The uncertainties associated with v 0 and other astrophysical parameters have been studied in refs.…”

“…The uncertainties associated with v 0 and other astrophysical parameters have been studied in refs. [72,74,75] in the context of ER (see ref. [164] for halo independent analysis).…”

Solar constraints on captured electrophilic dark matter

“…where ρ χ is the local DM density, f (u χ ) is the velocity distribution profile of DM, m χ is mass of the DM particle and R is the radius of the Sun, w(r) = u 2 χ + v 2 esc (r) is the velocity of a gravitationally focused DM particle at a distance r from the center of the Sun, v esc (r) being the escape velocity at that location. The galactic escape velocity of DM is given by u esc = 528 km/s [36,37]. The differential rate of DM-electron scattering that can trigger a velocity change from w(r) to v can be expressed as…”