Kinematics of the Milky way from the statistical analysis of the Gaia Data Release 3

TL;DR

This paper analyzes Gaia DR3 data to determine the Milky Way's kinematic parameters, revealing local velocities, galactic rotation speed, and vertical velocity gradients using advanced statistical and simulation methods.

Contribution

It introduces new statistical techniques for analyzing Gaia data and models the galaxy's kinematics with a simple Monte Carlo simulation, providing detailed local and global motion parameters.

Findings

Local solar velocity: (9.58, 16.25, 7.33) km/s

Galactic rotation velocity: approximately 234 km/s

Vertical velocity gradient: about 33.5 km/s/kpc

Abstract

The aim of the analysis of data from the Gaia Space Observatory is to obtain kinematic parameters of the collective motion of stars in a part of our galaxy. This research is based on a statistical analysis of the motion of {$55,038,539$} stars selected in different directions from the Sun up to a distance of 3--6 kpc. We developed statistical methods for the analysis working with input data represented by the full astrometric solution (five parameters). Using the proposed statistical methods, we obtained the local velocity of the Sun $\left( U_{\odot}% ,V_{\odot},W_{\odot}\right) =(9.58,16.25,7.33)\pm(0.05,0.04,0.02)_{stat}% \pm(0.7,0.9,0.1)_{syst}$ km/s and the rotation velocity of the galaxy at different radii. For the Sun's orbit radius, we obtained the velocity of the galaxy rotation$\ V_{c}\approx234\pm4$ km/s. Collective rotation slows down in the region under study linearly with distance from the disk plane: $\Delta V/\Delta Z\cong33.5~\mathrm{km\,s}^{-1}\mathrm{kpc}^{-1}$. We showed that the different kinematic characteristics and distributions, which depend on the position in the galaxy, can be well described in the studied 3D region by a simple Monte Carlo simulation model, representing an axisymmetric approximation of the galaxy kinematics. The optimal values of the six free parameters were tuned by comparison with the data.