Simulated Milky Way analogues: implications for dark matter direct searches

Abstract

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