Abstract
Local dark matter density, ρdm, is one of the crucial astrophysical inputs for the estimation of detection rates in dark matter direct search experi- ments. Knowing the value also helps us to investigate the shape of the Galactic dark halo, which is of importance for indirect dark matter searches, as well as for various studies in astrophysics and cosmology. In this work, we performed kinematics study of stars in the solar neighborhood to determine the local dark matter density. As tracers we used 95,543 K-dwarfs from Gaia DR2 inside a heliocentric cylinder with a radius of 150 pc and height 200 pc above and below the Galactic mid plane. Their positions and motions were analyzed, assum- ing that the Galaxy is axisymmetric and the tracers are in dynamical equilib- rium. We applied Jeans and Poisson equations to relate the observed quantities, i.e. vertical position and velocity, with the local dark matter density. The tilt term in the Jeans equation is considered to be small and is therefore neglected. Galactic disk is modelled to consist of a single exponential stellar disk, a thin gas layer, and dark matter whose density is constant within the volume consid- ered. Marginalization for the free parameters was performed with Bayesian theorem using Markov Chain Monte Carlo (MCMC) method. We find that ρdm= 0.0116 ± 0.0012 MO/pc or ρdm= 0.439 ± 0.046 GeV/cm3, in agreement within the range of uncertainty with results of several previous studies.
Highlights
Efforts to understand the properties of dark matter are constantly being made through both indirect and direct experiments
Local dark matter density, ρdm, is an important parameter for estimation of the detection rate of dark matter particles. ρdm is defined as the value of dark matter density in the solar neighborhood
There are no tight restrictions set by the term “local”, ρdm is commonly determined by examining a small volume around the Sun, typically within the height of a few hundred parsecs up to ∼ 103 pc from the Galactic mid plane [1]
Summary
Efforts to understand the properties of dark matter are constantly being made through both indirect and direct experiments. Aside from its importance to estimate the detection rate of dark matter particles, it is intriguing to obtain the value of ρdm, because knowing it can help revealing the actual shape of the Galactic dark halo – which has been assumed to have a spherical symmetry. This is done by comparing ρdm with the value obtained from global dark matter density profile through decomposition of Milky Way’s rotation curve [2, 3].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
