Simulated Milky Way analogues: implications for dark matter direct searches

Abstract

We study the implications of galaxy formation on dark matter direct detection using high resolution hydrodynamic simulations of Milky Way-like galaxies simulated within the eagle and apostle projects. We identify Milky Way analogues that satisfy observational constraints on the Milky Way rotation curve and total stellar mass. We then extract the dark matter density and velocity distribution in the Solar neighbourhood for this set of Milky Way analogues, and use them to analyse the results of current direct detection experiments. For most Milky Way analogues, the event rates in direct detection experiments obtained from the best fit Maxwellian distribution (with peak speed of 223 -289 km/s) are similar to those obtained directly from the simulations. As a consequence, the allowed regions and exclusion limits set by direct detection experiments in the dark matter mass and spin-independent cross section plane shift by a few GeV compared to the Standard Halo Model, at low dark matter masses. For each dark matter mass, the halo-to-halo variation of the local dark matter density results in an overall shift of the allowed regions and exclusion limits for the cross section. However, the compatibility of the possible hints for a dark matter signal from DAMA and CDMS-Si and null results from LUX and SuperCDMS is not improved.

Astrophysical uncertainties on the local dark matter distribution and direct detection experiments

“…Refs. [66,67] found that a Maxwellian speed distribution is a good fit to the speed distribution in their hydrodynamical simulations. This may be because adiabatic contraction makes the logarithmic slope of the density profile in the Solar neighbourhood closer to that of an isothermal sphere [67].…”

“…In early 2016 several studies of the local dark matter distribution in MW-like galaxies were published [66][67][68]. Borzognia et al [66] selected galaxies from the EAGLE [69] and APOSTLE [70] projects with masses in the range (10 12 − 10 13 M ⊙ ) that satisfied observational constraints on the MW rotation curve and stellar mass. Kelso et al [67] [68] studied four MW-like galaxies, with masses in the range 0.7 − 0.9 × 10 12 M ⊙ with a variety of different merger histories (i.e.…”

“…[63][64][65] found velocity distributions in hydrodynamical simulations of MW-like galaxies which deviated significantly, in different ways, from a Maxwellian distribution. In early 2016 several studies of the local dark matter distribution in MW-like galaxies were published [66][67][68]. Borzognia et al [66] selected galaxies from the EAGLE [69] and APOSTLE [70] projects with masses in the range (10 12 − 10 13 M ⊙ ) that satisfied observational constraints on the MW rotation curve and stellar mass.…”

The waning of the WIMP? A review of models, searches, and constraints

“…A mass, m a = √ 2 Φ , for this second field is originated by an explicit mass term 2 Φ Φ 2 /2 in Eq. (77). In this kind of setup it is rather natural to identify the pseudoscalar component with a pseudo-Goldstone boson associated to a U (1) global symmetry carried by the complex scalar Φ and then assumes that m a m S [298][299][300].…”

New constraints and discovery potential of sub-GeV dark matter with xenon detectors

“…Small deviations from a MB distribution are likely, as seen in numerical simulations, e.g. [42][43][44], and predicted by Earth-scattering effects, e.g. [45][46][47], but we do not consider them in this work.…”