The Dark Matter Density in the Solar Neighborhood reconsidered

TL;DR

This study suggests the local dark matter density is higher than previously thought due to doughnut-like substructures in the halo, which has implications for dark matter detection efforts.

Contribution

It introduces a model with doughnut-like dark matter substructures that better fit observational data, revising the local dark matter density estimate.

Findings

Local dark matter density increased by a factor of four

Doughnut-like substructures align with dust and star rings

Revised dark matter density impacts detection strategies

Abstract

Both the gas flaring and the dip in the rotation curve, which was recently reconfirmed with precise measurements using the VERA VLBI array in Japan, suggest doughnut-like substructure in the dark matter (DM) halo. A global fit to all available data shows that the data are indeed best described by an NFW DM profile complemented by two doughnut-like DM substructures with radii of 4.2 and 12.4 kpc, which coincide with the local dust ring and the Monocerus ring of stars, respectively. Both regions have been suggested as regions with tidal streams from "shredded" satellites. If real, the radial extensions of these nearby ringlike structures enhance the local dark matter density by a factor of four to about 1.3$\pm0.3$ GeV/cm$^3$. It is shown that i) this higher DM density is perfectly consistent with the local gravitational potential determining the surface density and the local matter density (Oort limit), ii) previous determinations of the surface density were biased by the assumption of a smoothly varying DM halo and iii) the s-shaped gas flaring is explained. Such a possible enhancement of the local DM density is of great interest for direct DM searches and would change the directional dependence for indirect DM searches.