The imprints of the Galactic bar on the thick disk with RAVE

Abstract

We study the kinematics of a local sample of stars, located within a cylinder of 500 pc radius centered on the Sun, in the RAVE dataset. We find clear asymmetries in the $v_R$-$v_{\varphi }$ velocity distributions of thin and thick disk stars: here are more stars moving radially outwards for low azimuthal velocities and more radially inwards for high azimuthal velocities. Such asymmetries have been previously reported for the thin disk as being due to the Galactic bar, but this is the first time that the same type of structures are seen in the thick disk. Our findings imply that the velocities of thick disk stars should no longer be described by Schwarzschild's, multivariate Gaussian or purely axisymmetric distributions. Furthermore, the nature of previously reported substructures in the thick disk needs to be revisited as these could be associated with dynamical resonances rather than to accretion events. It is clear that dynamical models of the Galaxy must fit the 3D velocity distributions of the disks, rather than the projected 1D, if we are to understand the Galaxy fully.

arXiv commentAccepted for publication in ApJL; 7 pages, 3 figures, 1 table

References in corpus (40)

• Local Kinematics and the Local Standard of Rest
• Trigonometric Parallaxes of High Mass Star Forming Regions: the Structure and Kinematics of the Milky Way
• The Milky Way Tomography with SDSS: I. Stellar Number Density Distribution
• SEGUE: A Spectroscopic Survey of 240,000 stars with g=14-20
• The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)
• 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
• The Proper Motion of Sgr A*: II. The Mass of Sgr A*
• Studies in Astronomical Time Series Analysis. VI. Bayesian Block Representations
• The Geneva-Copenhagen Survey of the Solar neighbourhood III. Improved distances, ages, and kinematics
• The Effect of the Outer Lindblad Resonance of the Galactic Bar on the Local Stellar Velocity Distribution
• Local kinematics of K and M giants from Coravel/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters
• The RAdial Velocity Experiment (RAVE): Fourth data release
• The Distribution of Nearby Stars in Velocity Space Inferred from Hipparcos Data
• The Third US Naval Observatory CCD Astrograph Catalog (UCAC3)
• The wobbly Galaxy: kinematics north and south with RAVE red clump giants
• A First Constraint on the Thick Disk Scale Length: Differential Radial Abundances in K Giants at Galactocentric Radii 4, 8, and 12 kpc
• The stellar velocity distribution in the solar neighbourhood
• Pieces of the puzzle: Ancient substructure in the Galactic disk
• The RAdial Velocity Experiment (RAVE): Third Data Release
• Deciphering The Last Major Invasion of the Milky Way Galaxy
• Is the Milky Way ringing? The hunt for high velocity streams
• Constraints on the Galactic Bar from the Hercules stream as traced with RAVE across the Galaxy
• Kinematic modelling of the Milky Way using the RAVE and GCS stellar surveys
• Radial and vertical flows induced by galactic spiral arms: likely contributors to our "wobbly Galaxy''
• Origin and evolution of moving groups I. Characterization in the observational kinematic-age-metallicity space
• The Extragalactic Origin of the Arcturus Group
• Understanding the spiral structure of the Milky Way using the local kinematic groups
• Radial Migration in Galactic Thick Discs
• New distances to RAVE stars
• Galactic kinematics and dynamics from RAVE stars
• Automatic stellar spectra parameterisation in the IR CaII triplet region
• A Recent Lindblad Resonance in the Solar Neighbourhood
• In the thick of it: metal-poor disc stars in RAVE
• Kinematic groups beyond the Solar neighbourhood with RAVE
• Exploring the Morphology of RAVE Stellar Spectra
• The Solar neighbourhood in angle coordinates: the Hyades moving group
• Through thick and thin: Structure of the Galactic thick disc from extragalactic surveys
• A 10,000 star spectroscopic survey of the thick disk-halo interface : Phase-space sub-structure in the thick disk
• Mapping the Asymmetric Thick Disk: III. The Kinematics and Interaction with the Galactic Bar

Cited by in corpus (16)

• The Radial Velocity Experiment (RAVE): Fifth Data Release
• One large blob and many streams frosting the nearby stellar halo in Gaia DR2
• The Galactic Disc in Action Space as seen by Gaia DR2
• The Brown Dwarf Kinematics Project (BDKP). IV. Radial Velocities of 85 Late-M and L dwarfs with MagE
• Spiral arm crossings inferred from ridges in Gaia stellar velocity distributions
• The Surface Density Profile of the Galactic Disk from the Terminal Velocity Curve
• Spiral and bar driven peculiar velocities in Milky Way sized galaxy simulations
• Chemo-kinematics of the Milky Way spiral arms and bar resonances: connection to ridges and moving groups in the Solar vicinity
• The GALAH Survey: Stellar streams and how stellar velocity distributions vary with Galactic longitude, hemisphere and metallicity
• The outer disc in shambles: blind detection of Monoceros and ACS with Gaia's astrometric sample
• Correlations between age, kinematics, and chemistry as seen by the RAVE survey
• Asymmetric metallicity patterns in the stellar velocity space with RAVE
• Frequencies, chaos and resonances: a study of orbital parameters of nearby thick disc and halo stars
• Local Stellar Kinematics from RAVE data -- VIII. Effects of the Galactic Disc Perturbations on Stellar Orbits of Red Clump Stars
• Gaia DR2 white dwarfs in the Hercules stream
• Collisionless Boltzmann equation approach for the study of stellar discs within barred galaxies