Dark matter local density determination: recent observations and future prospects

Abstract

This report summarises progress made in estimating the local density of dark matter (ρ DM, ), a quantity that is especially important for dark matter direct detection experiments. We outline and compare the most common methods to estimate ρ DM, and the results from recent studies, including those that have benefited from the observations of the ESA/Gaia satellite. The result of most local analyses coincide within a range of ρ DM, 0.4-0.6 GeV cm −3 = 0.011-0.016 M /pc 3 , while a slightly lower range of ρ DM, 0.3-0.5 GeV cm −3 = 0.008-0.013 M /pc 3 is preferred by most global studies. In light of recent discoveries, we discuss the importance of going beyond the approximations of what we define as the ideal Galaxy (a steady-state Galaxy with axisymmetric shape and a mirror symmetry across the mid-plane) in order to improve the precision of ρ DM, measurements. In particular, we review the growing evidence for local disequilibrium and broken symmetries in the present configuration of the Milky Way, as well as uncertainties associated with the galactic distribution of baryons. Finally, we comment on new ideas that have been proposed to further constrain the value of ρ DM, , most of which would benefit from Gaia's final data release.

Reevaluation of the cosmic antideuteron flux from cosmic-ray interactions and from exotic sources

“…The Galactic dark-matter distribution ρ( r) can be determined from kinematic tracers [93]. There is uncertainty both in the local density at the position of the Sun r , as well as in the shape of the distribution towards the inner Galaxy.…”

Dark Matter in Astrophysics/Cosmology

“…assumptions of equilibrium and spherical symmetry, and modelling uncertainties, are significant. For extensive details see Read's 2014 review [69], and for a more recent review, see de Salas & Widmark [70].…”

Charting galactic accelerations II: how to 'learn' accelerations in the solar neighbourhood

“…For example, if the acceleration due to the luminous component is known, then we can calculate the density distribution of dark matter, uncovering any substructures and measuring the ambient dark matter density in the solar system. This latter number is of great importance in particle physics, as it is a key parameter in the interpretation of results of dark matter direct detection experiments (Read 2014;de Salas & Widmark 2021). Alternatively, we can use the direction of the acceleration vectors to constrain alternative theories of gravity such as Modified Newtonian Dynamics (MOND; Milgrom 1983) or similar.…”

“…Note that either treatment necessitates the assumption of dynamical equilibrium, so that the time-derivative term in equation ( 1) can be neglected. The review articles by Read (2014) and de Salas & Widmark (2021) give good overviews of how these methods work in practice.…”