Is the sky falling? Searching for stellar streams in the local Milky Way disc in the CORAVEL and RAVE surveys

Abstract

We have searched for in-falling stellar streams on to the local Milky Way disc in the CORAVEL and RAVE surveys. The CORAVEL survey consists of local dwarf stars (Nordstrom et al. Geneva-Copenhagen survey) and local Famaey et al. giant stars. We select RAVE stars with radial velocities that are sensitive to the Galactic vertical space velocity (Galactic latitude b < -45 deg). Kuiper statistics have been employed to test the symmetry of the Galactic vertical velocity distribution functions in these samples for evidence of a net vertical flow that could be associated with a (tidal?) stream of stars with vertically coherent kinematics. In contrast to the `Field of Streams' found in the outer halo, we find that the local volumes of the solar neighbourhood sampled by the CORAVEL dwarfs (complete within ~3 x 10^-4 kpc^3), CORAVEL giants (complete within ~5 x 10^-2 kpc^3) and RAVE (5-15% complete within ~8 kpc^3) are devoid of any vertically coherent streams containing hundreds of stars. This is sufficiently sensitive to allow our RAVE sample to rule out the passing of the tidal stream of the disrupting Sagittarius (Sgr) dwarf galaxy through the solar neighbourhood. This agrees with the most recent determination of its orbit and dissociates it from the Helmi et al. halo stream. Our constraints on the absence of the Sgr stream near the Sun could prove a useful tool for discriminating between Galactic potential models. The lack of a net vertical flow through the solar neighbourhood in the CORAVEL giants and RAVE samples argues against the Virgo overdensity crossing the disc near the Sun. There are no vertical streams in the CORAVEL giants and RAVE samples with stellar densities >1.6 x 10^4 and 1.5 x 10^3 stars kpc^-3 respectively and therefore no evidence for locally enhanced dark matter.

Accepted for publication in MNRAS, 25 pages, 22 figures, 9 tables

References in corpus (13)

• The Radial Velocity Experiment (RAVE): first data release
• The RAVE Survey: Constraining the Local Galactic Escape Speed
• The Geneva-Copenhagen Survey of the Solar neighbourhood II. New uvby calibrations and rediscussion of stellar ages, the G dwarf problem, age-metallicity diagram, and heating mechanisms of the disk
• An Orphan in the "Field of Streams"
• The Origin of the Bifurcation in the Sagittarius Stream
• Detection of a 60 Degree-Long Dwarf Galaxy Debris Stream
• The Overdensity in Virgo, Sagittarius Debris, and the Asymmetric Spheroid
• Re-visiting the relations: Galactic thin disc age-velocity dispersion relation
• Halo Star Streams in the Solar Neighborhood
• High-resolution spectroscopy of RGB stars in the Sagittarius Streams. I. Radial velocities and chemical abundances
• Is Ursa Major II the Progenitor of the Orphan Stream?
• Kinematic Structure in the Galactic Halo at the North Galactic Pole: RR Lyrae and BHB Stars show different kinematics
• CADIS has seen the Virgo overdensity and parts of the Monoceros and `Orphan' streams in retrospect

Cited by in corpus (16)

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• Interpreting Dark Matter Direct Detection Independently of the Local Velocity and Density Distribution
• Estimation of the Tilt of the Stellar Velocity Ellipsoid from RAVE and Implications for Mass Models
• Expected high energy emission from GRB 080319B and origins of the GeV emission of GRBs 080514B, 080916C and 081024B
• Diffuse interstellar bands in RAVE Survey spectra
• Double-lined Spectroscopic Binary Stars in the Radial Velocity Experiment Survey
• Dark Matter Direct Search Rates in Simulations of the Milky Way and Sagittarius Stream
• On the Implications of Late Internal Dissipation for Shallow-Decay Afterglow Emission and Associated High-Energy Gamma-Ray Signals
• Dynamically Tagged Groups of Metal-Poor Stars II. The Radial Velocity Experiment Data Release 6
• Do the nearby BHB stars belong to the Thick Disk or the Halo?
• The Galactic thin and thick disk
• Galactic Kinematics Derived from Data in the RAVE5, UCAC4, PPMXL, and Gaia TGAS Catalogs
• High-Drag Interstellar Objects And Galactic Dynamical Streams
• RAVE- First Results and Second Data Release