Validation of the Bond et al. (2010) SDSS-derived kinematic models for the Milky Way's disk and halo stars with Gaia Data Release 3 proper motion and radial velocity data

TL;DR

This study validates the Bond et al. (2010) kinematic models of the Milky Way's disk and halo stars using Gaia DR3 data, confirming their accuracy in predicting stellar velocity distributions and gradients.

Contribution

The paper provides the first comprehensive validation of the SDSS-based kinematic models with Gaia DR3 data, confirming their applicability across different Galactic regions.

Findings

Bond et al. models accurately predict Gaia-measured velocities.

Model reproduces the skewed velocity distribution of disk stars.

Velocity ellipsoid invariance confirmed for halo stars up to 15 kpc.

Abstract

We validate the Bond et al. (2010) kinematic models for the Milky Way's disk and halo stars with Gaia Data Release 3 data. Bond et al. constructed models for stellar velocity distributions using stellar radial velocities measured by the Sloan Digital Sky Survey (SDSS) and stellar proper motions derived from SDSS and the Palomar Observatory Sky Survey astrometric measurements. These models describe velocity distributions as functions of position in the Galaxy, with separate models for disk and halo stars that were labeled using SDSS photometric and spectroscopic metallicity measurements. We find that the Bond et al. model predictions are in good agreement with recent measurements of stellar radial velocities and proper motions by the Gaia survey. In particular, the model accurately predicts the skewed non-Gaussian distribution of rotational velocity for disk stars and its vertical gradient, as well as the dispersions for all three velocity components. Additionally, the spatial invariance of velocity ellipsoid for halo stars when expressed in spherical coordinates is also confirmed by Gaia data at galacto-centric radial distances of up to 15 kpc.