Derivation of the anisotropy profile, constraints on the local velocity dispersion, and implications for direct detection

Abstract

We study the implications of a pseudo-phase-space density power-law for the anisotropy profile of a Milky Way-like dark matter halo. Requiring that the anisotropy parameter does not take non-physical values within the virial radius places a maximum value on the local radial velocity dispersion. For a plausible range of halo parameters, it is possible to take a local total velocity dispersion of up to about $300km/s$. Making this choice uniquely specifies the anisotropy and dispersion profiles. We introduce a way to model the local velocity distribution that incorporates this anisotropy and study the impact on direct detection.

Detailed derivation deferred to an appendix. Plots reworked to reflect uncertainty in the halo parameters, and some rewording. Same procedure and conclusions. Accepted for publication in JCAP. 15 pages, 8 figures

References in corpus (7)

• Phase-space structure in the local dark matter distribution and its signature in direct detection experiments
• A universal density slope - velocity anisotropy relation for relaxed structures
• Halo-to-Halo Similarity and Scatter in the Velocity Distribution of Dark Matter
• Anisotropic dark matter distribution functions and impact on WIMP direct detection
• Effects of Velocity-Dependent Dark Matter Annihilation on the Energy Spectrum of the Extragalactic Gamma-ray Background
• Dark Matter Halos: Velocity Anisotropy -- Density Slope Relation
• The behaviour of shape and velocity anisotropy in dark matter haloes

Cited by in corpus (8)

• Directional axion detection
• Anatomy of Eddington-like inversion methods in the context of dark matter searches
• Robust cosmic-ray constraints on $p$-wave annihilating MeV dark matter
• Predicting the dark matter velocity distribution in galactic structures: tests against hydrodynamic cosmological simulations
• Anisotropic q-Gaussian velocity distributions in LambdaCDM halos
• EDGE: The shape of dark matter haloes in the faintest galaxies
• Discrimination of anisotropy in dark matter velocity distribution with directional detectors
• Combined dark matter search towards dwarf spheroidal galaxies with Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS