Gaussian Process Model for the Local Stellar Velocity Field from Gaia Data Release 2

Abstract

We model the local stellar velocity field using position and velocity measurements for 4M stars from the second data release of Gaia. We determine the components of the mean or bulk velocity in ~27k spatially-defined bins. Our assumption is that these quantities constitute a Gaussian process where the correlation between the bulk velocity at different locations is described by a simple covariance function or kernel. We use a sparse Gaussian process algorithm based on inducing points to construct a non-parametric, smooth, and differentiable model for the underlying velocity field. We estimate the Oort constants A, B, C, and K and find values in excellent agreement with previous results. Maps of the velocity field within 2 kpc of the Sun reveal complicated substructures, which provide clear evidence that the local disk is in a state of disequilibrium. We present the first 3D map of the divergence of the stellar velocity field and identify regions of the disk that may be undergoing compression and rarefaction.

arXiv comment10 pages, 10 figures; typos corrected, figure format

References in corpus (44)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Gaia Data Release 2. Summary of the contents and survey properties
• SEGUE: A Spectroscopic Survey of 240,000 stars with g=14-20
• The Radial Velocity Experiment (RAVE): first data release
• The PPMXL catalog of positions and proper motions on the ICRS. Combining USNO-B1.0 and 2MASS
• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• Vertical waves in the solar neighbourhood in Gaia DR2
• Gaia Data Release 2: Mapping the Milky Way disc kinematics
• First GLIMPSE Results on the Stellar Structure of the Galaxy
• Galactic Kinematics of Cepheids from Hipparcos Proper Motions
• Galactoseismology: Discovery of Vertical Waves in the Galactic Disk
• Galactic Rotation and Solar Motion from Stellar Kinematics
• Footprints of the Sagittarius dwarf galaxy in the $Gaia$ data set
• The wobbly Galaxy: kinematics north and south with RAVE red clump giants
• Vertical density waves in the Milky Way disc induced by the Sagittarius Dwarf Galaxy
• Gaia Data Release 2: Properties and validation of the radial velocities
• Distances and parallax bias in Gaia DR2
• Gaia Data Release 3: Mapping the asymmetric disc of the Milky Way
• Substructure in bulk velocities of Milky Way disk stars
• Refining the Oort and Galactic constants
• Galactic rotation in Gaia DR1
• Radial Distribution of Stellar Motions in Gaia DR2
• The properties of the local spiral arms from RAVE data: two-dimensional density wave approach
• Proceedings of the Twenty-Ninth Conference on Uncertainty in Artificial Intelligence (2013)
• The Oort Constants Measured from Proper Motions
• The power spectrum of the Milky Way: Velocity fluctuations in the Galactic disk
• Gas and Stellar Motions and Observational Signatures of Co-Rotating Spiral Arms
• Bending Waves in the Milky Way's disc from halo substructure
• Is the Milky Way still breathing? RAVE-Gaia streaming motions
• Exploring the Sgr-Milky-Way-disc interaction using high resolution N-body simulations
• More than just a wrinkle: A wave-like pattern in radial velocity vs. angular momentum from Gaia Data
• Spiral and bar driven peculiar velocities in Milky Way sized galaxy simulations
• Dynamics of Disks and Warps
• Mapping the Galactic disk with the LAMOST and Gaia Red clump sample. II. 3D asymmetrical kinematics of mono-age populations in the disk between 6$-14$ \,kpc
• Dynamics for Galactic Archaeology
• Gaia-DR2 extended kinematical maps. Part II: Dynamics in the Galactic disk explaining radial and vertical velocities
• Local Stellar Kinematics and Oort Constants from the LAMOST A-type Stars
• The stellar kinematics of co-rotating spiral arms in Gaia mock observations
• Measuring the vertical response of the Galactic disc to an infalling satellite
• Evidence of a vertical kinematic oscillation beyond the Radcliffe Wave
• Large-scale three-dimensional Gaussian process extinction mapping
• A Map of the Local Velocity Substructure in the Milky Way Disk
• Kinematics of the Milky Way from the Gaia EDR3 red giants and sub-giants
• Three-Dimensional Kinematics of Classical Cepheids

Cited by in corpus (6)

• The origin and fate of the Gaia phase-space snail
• Mapping Milky Way disk perturbations in stellar number density and vertical velocity using Gaia DR3
• The Corona Australis star formation complex is accelerating away from the Galactic plane
• A new kinematic model of the Galaxy: analysis of the stellar velocity field from Gaia Data Release 3
• The missing radial velocities of Gaia: a catalogue of Bayesian estimates for DR3
• Two-point correlation function studies for the Milky Way: discovery of spatial clustering from disk excitations and substructure