Reconstructing the three-dimensional local dark matter velocity distribution

Abstract

Directionally sensitive dark matter (DM) direct detection experiments present the only way to observe the full three-dimensional velocity distribution of the Milky Way halo local to Earth. In this work we compare methods for extracting information about the local DM velocity distribution from a set of recoil directions and energies in a range of hypothetical directional and non-directional experiments. We compare a model independent empirical parameterisation of the velocity distribution based on an angular discretisation with a model dependent approach which assumes knowledge of the functional form of the distribution. The methods are tested under three distinct halo models which cover a range of possible phase space structures for the local velocity distribution: a smooth Maxwellian halo, a tidal stream and a debris flow. In each case we use simulated directional data to attempt to reconstruct the shape and parameters describing each model as well as the DM particle properties. We find that the empirical parametrisation is able to make accurate unbiased reconstructions of the DM mass and cross section as well as capture features in the underlying velocity distribution in certain directions without any assumptions about its true functional form. We also find that by extracting directionally averaged velocity parameters with this method one can discriminate between halo models with different classes of substructure.

15 pages, 5 figures. v2: minor changes to match version published in PRD

References in corpus (24)

• The Local Dark Matter Density
• Dark Matter Search Results from the PICO-2L C${}_3$F${}_8$ Bubble Chamber
• Phase-space structure in the local dark matter distribution and its signature in direct detection experiments
• Annual Modulation of Dark Matter in the Presence of Streams
• The Dark Matter at the End of the Galaxy
• Interpreting Dark Matter Direct Detection Independently of the Local Velocity and Density Distribution
• Halo-to-Halo Similarity and Scatter in the Velocity Distribution of Dark Matter
• Directional Dark Matter Detection Beyond the Neutrino Bound
• Markov Chain Monte Carlo analysis to constrain Dark Matter properties with directional detection
• Dark Matter Direct Search Rates in Simulations of the Milky Way and Sagittarius Stream
• Taking Halo-Independent Dark Matter Methods Out of the Bin
• Observation of the 'head-tail' effect in nuclear recoils of low-energy neutrons
• The median recoil direction as a WIMP directional detection signal
• Directional detection of dark matter streams
• Probing the Local Velocity Distribution of WIMP Dark Matter with Directional Detectors
• First measurement of the Head-Tail directional nuclear recoil signature at energies relevant to WIMP dark matter searches
• Studying generalised dark matter interactions with extended halo-independent methods
• Probing WIMP particle physics and astrophysics with direct detection and neutrino telescope data
• Consequences of statistical sense determination for WIMP directional detection
• Assessing Compatibility of Direct Detection Data: Halo-Independent Global Likelihood Analyses
• Reanalysis of nuclear spin matrix elements for dark matter spin-dependent scattering
• Discretising the velocity distribution for directional dark matter experiments
• Comparing readout strategies to directly detect dark matter
• A halo-independent lower bound on the dark matter capture rate in the Sun from a direct detection signal

Cited by in corpus (2)

• Axion astronomy with microwave cavity experiments
• Time-integrated directional detection of dark matter