Riding the kinematic waves in the Milky Way disk with Gaia

Abstract

Gaia DR2 has delivered full-sky 6-D measurements for millions of stars, and the quest to understand the dynamics of our Galaxy has entered a new phase. Our aim is to reveal and characterize the kinematic sub-structure of the different Galactic neighbourhoods, to form a picture of their spatial evolution that can be used to infer the Galactic potential, its evolution and its components. We take ~5 million stars in the Galactic disk from the Gaia DR2 catalogue and build the velocity distribution of many different Galactic Neighbourhoods distributed along 5 kpc in Galactic radius and azimuth. We decompose their distribution of stars in the V_R-V_phi plane with the wavelet transformation and asses the statistical significance of the structures found. We detect many kinematic sub-structures (arches and more rounded groups) that diminish their azimuthal velocity as a function of Galactic radius in a continuous way, connecting volumes up to 3 kpc apart in some cases. The decrease rate is, on average, of ~23 km/s/kpc. In azimuth, the kinematic sub-structures present much smaller variations. We also observe a duality in their behaviour: some conserve their vertical angular momentum with radius (e.g., Hercules), while some seem to have nearly constant kinetic energy (e.g., Sirius). These two trends are consistent with the approximate predictions of resonances and of phase mixing, respectively. Besides, the overall spatial evolution of Hercules is consistent with being related to the Outer Lindblad Resonance of the Bar. We also detect structures without apparent counterpart in the vicinity of the Sun. The various trends observed and their continuity with radius and azimuth allows for future work to deeply explore the parameter space of the models. Also, the characterization of extrasolar moving groups opens the opportunity to expand our understanding of the Galaxy beyond the Solar Neighbourhood.

16 pages. Submitted to Astronomy and Astrophysics on 24th of May, 2018. Related on-line material available (see Appendix B)

References in corpus (26)

• Gaia Data Release 2. Summary of the contents and survey properties
• scikit-image: Image processing in Python
• The Gaia mission
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• The Radial Velocity Experiment (RAVE): first data release
• The GALAH Survey: Scientific Motivation
• Gaia Data Release 2: using Gaia parallaxes
• A dynamically young and perturbed Milky Way disk
• Gaia Data Release 2: Mapping the Milky Way disc kinematics
• One large blob and many streams frosting the nearby stellar halo in Gaia DR2
• Estimating distances from parallaxes. III. Distances of two million stars in the Gaia DR1 catalogue
• Is the Milky Way ringing? The hunt for high velocity streams
• Origin and evolution of moving groups I. Characterization in the observational kinematic-age-metallicity space
• Radial Distribution of Stellar Motions in Gaia DR2
• Stellar Kinematic Constraints on Galactic Structure Models Revisited: Bar and Spiral Arm Resonances
• Tracing the Hercules stream with Gaia and LAMOST: new evidence for a fast bar in the Milky Way
• The 4:1 Outer Lindblad Resonance of a long slow bar as a potential explanation for the Hercules stream
• Spiral arm crossings inferred from ridges in Gaia stellar velocity distributions
• The GALAH Survey and Gaia DR2: (Non)existence of five sparse high-latitude open clusters
• The Hercules stream as seen by APOGEE-2 South
• The GALAH Survey: Stellar streams and how stellar velocity distributions vary with Galactic longitude, hemisphere and metallicity
• Tracing the Hercules stream around the Galaxy
• Stellar Stream Candidates in the Solar Neighborhood Found in the LAMOST DR3 and TGAS
• Kinematic structures of the Solar neighbourhood revealed by Gaia DR1/TGAS and RAVE
• The velocity distribution in the solar neighbourhood from the LAMOST pilot survey
• Collisionless Boltzmann equation approach for the study of stellar discs within barred galaxies

Cited by in corpus (81)

• Footprints of the Sagittarius dwarf galaxy in the $Gaia$ data set
• Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18
• Gaia Data Release 3: Mapping the asymmetric disc of the Milky Way
• Galactic spiral structure revealed by Gaia EDR3
• The signatures of the resonances of a large Galactic bar in local velocity space
• The GALAH survey and Gaia DR2: Linking ridges, arches and vertical waves in the kinematics of the Milky Way
• Gaia Early Data Release 3: The Galactic anticentre
• Fluctuations in galactic bar parameters due to bar-spiral interaction
• On the Milky Way spiral arms from open clusters in Gaia EDR3
• Signatures of resonance and phase mixing in the Galactic disc
• Mapping the Milky Way Disk with Gaia DR3: 3D extended kinematic maps and rotation curve to $\approx 30$ kpc
• Gaia Data Release 3: Chemical cartography of the Milky Way
• Hic sunt dracones: Cartography of the Milky Way spiral arms and bar resonances with Gaia Data Release 2
• An all-sky proper motion map of the Sagittarius stream using Gaia DR2
• Kinematics with Gaia DR2: The Force of a Dwarf
• Chemo-kinematics of the Milky Way spiral arms and bar resonances: connection to ridges and moving groups in the Solar vicinity
• Trojans in the Solar Neighborhood
• Trimodal structure of Hercules stream explained by originating from bar resonances
• Measuring the local matter density using Gaia DR2
• Dissecting the Phase Space Snail Shell
• Galactic Bar Resonances Inferred from Kinematically Hot Stars in Gaia EDR3
• Tidally induced spiral arm wraps encoded in phase space
• Tracing Hercules in Galactic azimuth with Gaia DR2
• Vertical Phase Mixing across the Galactic Disk
• Exploring the origin of moving groups and diagonal ridges by simulations of stellar orbits and birthplaces
• From a Different Star: 3I/ATLAS in the context of the Ōtautahi-Oxford interstellar object population model
• Measuring the vertical response of the Galactic disc to an infalling satellite
• Spiral-like features in the disc revealed by Gaia DR3 radial actions
• Gaia Data Release 3: spectroscopic binary-star orbital solutions. The SB1 processing chain
• The bar resonances and low angular momentum moving groups in the Galaxy revealed by stellar ages
• Moving groups across Galactocentric radius with Gaia DR3
• Weighing the Galactic disk using phase-space spirals III. Probing distant regions of the disk using the Gaia EDR3 proper motion sample
• The stellar halo in Local Group Hestia simulations II. The accreted component
• From ridges in the velocity distribution to wiggles in the rotation curve
• Diagonal Ridge pattern of different age populations found in Gaia DR2 with LAMOST Main-Sequence-Turn-Off and OB type Stars
• From ridges to manifolds: 3D characterization of the moving groups in the Milky Way disc
• The outer disc in shambles: blind detection of Monoceros and ACS with Gaia's astrometric sample
• The Great Wave: Evidence of a large-scale vertical corrugation propagating outwards in the Galactic disc
• The Milky Way Bar Pattern Speed using Hercules and Gaia DR3
• A new resonance-like feature in the outer disc of the Milky Way
• Phase spirals in cosmological simulations of Milky Way-size galaxies
• Disentangling the Arcturus stream
• 2D chemical evolution models II. Effects of multiple spiral arm patterns on O, Eu, Fe and Ba abundance gradients
• Radial phase spirals in the Solar neighbourhood
• The HR 1614 moving group is not a dissolving cluster
• On the Galactic rotation curve inferred from the Jeans equations Assessing its robustness using Gaia DR3 and cosmological simulations
• A Holistic Review of a Galactic Interaction
• Predicting Interstellar Object Chemodynamics with Gaia
• Galactic resonance rings. Modelling of motions in the wide solar neighborhood
• Robust Clustering of the Local Milky Way Stellar Kinematic Substructures with Gaia eDR3
• Elemental abundances distributions in (R, $V_{\varphi }$) plane with LAMOST DR5 and Gaia DR2
• Radial Wave in the Galactic Disk: New Clues to Discriminate Different Perturbations
• The Reduced Proper Motion selected halo: methods and description of the catalogue
• Tracing the Origin of Moving Groups. III. Detecting Moving Groups in The LAMOST DR7
• Evidence for Co-rotation Origin of Super Metal Rich Stars in LAMOST-Gaia: Multiple Ridges with a Similar Slope in phi versus Lz Plane
• Radial and azimuthal gradients of the moving groups in Gaia DR3: The slow/fast bar degeneracy problem
• A non-axisymmetric potential for the Milky Way disk
• Limitations and rotation of the two-armed phase spiral in the Milky Way stellar disc
• Quantifying torque from the Milky Way bar using Gaia DR2
• Dynamically Produced Moving Groups in Interacting Simulations
• Measuring the Streaming motion in the Milky Way disc with Gaia EDR3 +
• Gaia DR2 white dwarfs in the Hercules stream
• On the Migration Origin of the Hercules Moving Group with GAIA, LAMOST, APOGEE, and GALAH Surveys
• Non-equilibrium in the Solar Neighbourhood using dynamical modelling with Gaia DR2
• Dynamical streams in the local stellar halo
• A New Cold Stream near the Southern Galactic Pole
• Chemodynamical Ages of Small-Scale Kinematic Structures of the Galactic Disc in the Solar Neighborhood from ~250,000 K and M Dwarfs
• Kinematic origin of white dwarfs in the solar neighborhood
• Kinematic-Chemical analysis and Time tagging for the Diagonal Ridge Structure of the Galactic Outer Disk with LAMOST Red Giant Branch Stars
• Dynamics of tidal spiral arms: Machine learning-assisted identification of equations and application to the Milky Way
• Partitioning the Galactic Halo with Gaussian Mixture Models
• Resolving local and global kinematic signatures of satellite mergers with billion particle simulations
• A new moving group in the Local Arm
• Moving Groups in the Solar Neighborhood with Gaia, APOGEE, GALAH, and LAMOST: Dynamical Effects Gather Gas and the Ensuing Star Formation Plays an Important Role in Shaping the Stellar Velocity Distributions
• The disturbed outer Milky Way disc
• Wrinkles in Time. II. Stellar Age Trends in Kinematic Signatures from Transient Spiral Structure
• Deep chemical tagging -- Identifying open clusters and moving groups in chemical space with graph attention networks
• Searching for and characterizing halo substructures with the GALAH DR4 survey
• Perturbed distribution functions with accurate action estimates for the Galactic disc
• Kinematics of the Milky way from the statistical analysis of the Gaia Data Release 3
• Galactic tides in the Solar System within a non-axisymmetric Milky Way model adjusted to Gaia data