2019A&A...623A..30W


C.D.S. - SIMBAD4 rel 1.7 - 2020.06.06CEST07:38:58

2019A&A...623A..30W - Astronomy and Astrophysics, volume 623A, 30-30 (2019/3-1)

Measuring the local matter density using Gaia DR2.

WIDMARK A.

Abstract (from CDS):


Aims. We determine the total dynamical matter density in the solar neighbourhood using the second Gaia data release (DR2).
Methods. The dynamical matter density distribution is inferred in a framework of a Bayesian hierarchical model, which accounts for position and velocity of all individual stars, as well as the full error covariance matrix of astrometric observables, in a joint fit of the vertical velocity distribution and stellar number density distribution. This was done for eight separate data samples, with different cuts in observed absolute magnitude, each containing about 25 000 stars. The model for the total matter density does not rely on any underlying baryonic model, although we assumed that it is symmetrical, smooth, and monotonically decreasing with distance from the mid-plane.
Results. We infer a density distribution which is strongly peaked in the region close to the Galactic plane (≤60pc), for all eight stellar samples. Assuming a baryonic model and a dark matter halo of constant density, this corresponds to a surplus surface density of approximately 5-9M/pc2. For the Sun's position and vertical velocity with respect to the Galactic plane, we infer Z=4.76±2.27pc and W=7.24±0.19km/s.
Conclusions. These results suggest a surplus of matter close to the Galactic plane, possibly explained by an underestimated density of cold gas. We discuss possible systematic effects that could bias our result, for example unmodelled non-equilibrium effects, and how to account for such effects in future extensions of this work.

Abstract Copyright: © ESO 2019

Journal keyword(s): Galaxy: kinematics and dynamics - Galaxy: disk - solar neighborhood - astrometry

Errata: erratum vol. 636, art. C1 (2020)

Status at CDS:  

Simbad objects: 1

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Number of rows : 1

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11469 0

    Equat.    Gal    SGal    Ecl

C.D.S. - SIMBAD4 rel 1.7 - 2020.06.06CEST07:38:58

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NAME Gal Center -- Region defined in the sky
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    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
ICRS coord. (ep=J2000) :
17 45 40.04 -29 00 28.1 [ ] E ~
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
FK4 coord. (ep=B1950 eq=1950) :
17 42 29.31 -28 59 18.5 [ ]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
Gal coord. (ep=J2000) :
359.94425 -00.04616 [ ]
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NAME Gal Centre HESS J1745-290 NAME Gal Center TeV J1745-290
GAL 000.0+00.0 NAME Galactic Centre NAME Galactic Center VER J1745-290

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2020.06.06-07:38:58

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