Simulated Milky Way analogues: implications for dark matter direct searches

TL;DR

This study uses high-resolution hydrodynamic simulations of Milky Way-like galaxies to analyze how galaxy formation impacts dark matter detection experiments, revealing that local dark matter properties vary and affect experimental constraints.

Contribution

It provides a detailed analysis of local dark matter distributions in Milky Way analogues from simulations, improving understanding of their impact on direct detection experiment results.

Findings

Event rates from simulations align with Maxwellian models.

Local dark matter density variations shift detection limits.

Compatibility of experimental hints and null results remains unchanged.

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.