Dark matter in the Milky Way: Measurements up to 3 kpc from the Galactic plane above the Sun

TL;DR

This study measures the dark matter density and halo shape near the Sun by analyzing red giant stars up to 3.5 kpc from the Galactic plane using Gaia data, providing key insights into the Milky Way's mass distribution.

Contribution

It offers a direct measurement of the local dark matter density and halo flattening using stellar kinematics, improving understanding of the Milky Way's dark matter halo structure.

Findings

Dark matter density at solar position: 0.0128±0.0008 GeV/cm³

Halo flattening parameter: 0.843±0.035

Dark matter halo density shape: 0.781±0.055

Abstract

We probe the gravitational force perpendicular to the Galactic plane at the position of the Sun based on a sample of red giants, with measurements taken from the DR3 Gaia catalogue. Measurements far out of the Galactic plane up to 3.5 kpc allow us to determine directly the total mass density, where dark matter is dominant and the stellar and gas densities are very low. In a complementary way, we have also used a new determination of the local baryonic mass density to help determine the density of dark matter in the Galactic plane at the solar position. For the local mass density of dark matter, we obtained $\rho_\mathrm{dm}$=0.0128$\pm $0.0008= 0.486 $\pm$0.030 Gev cm$^{-3}$. For the flattening of the gravitational potential of the dark halo, it is $q_\mathrm{\phi,h}$=0.843$\pm0.035$. For its density, $q_\mathrm{\rho,h}$=0.781$\pm$0.055.