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Is the Milky Way still breathing? RAVE-Gaia streaming motions

Carrillo, I.; Minchev, I.; Kordopatis, G.; Steinmetz, M.; Binney, J.; Anders, F.; Bienaymé, O.; Bland-Hawthorn, J.; Famaey, B. and Freeman, K. C., et al. (2018) In Monthly Notices of the Royal Astronomical Society 475(2). p.2679-2696
Abstract

We use data from the Radial Velocity Experiment (RAVE) and the Tycho-Gaia astrometric solution (TGAS) catalogue to compute the velocity fields yielded by the radial (VR), azimuthal (Vϕ),and vertical (Vz) components of associated Galactocentric velocity. We search in particular for variation in all three velocity components with distance above and below the disc midplane, as well as how each component of Vz (line-of-sight and tangential velocity projections) modifies the obtained vertical structure. To study the dependence of velocity on proper motion and distance, we use two main samples: a RAVE sample including proper motions from the Tycho-2, PPMXL, and UCAC4 catalogues, and a RAVE-TGAS sample with... (More)

We use data from the Radial Velocity Experiment (RAVE) and the Tycho-Gaia astrometric solution (TGAS) catalogue to compute the velocity fields yielded by the radial (VR), azimuthal (Vϕ),and vertical (Vz) components of associated Galactocentric velocity. We search in particular for variation in all three velocity components with distance above and below the disc midplane, as well as how each component of Vz (line-of-sight and tangential velocity projections) modifies the obtained vertical structure. To study the dependence of velocity on proper motion and distance, we use two main samples: a RAVE sample including proper motions from the Tycho-2, PPMXL, and UCAC4 catalogues, and a RAVE-TGAS sample with inferred distances and proper motions from the TGAS and UCAC5 catalogues. In both samples, we identify asymmetries in VR and Vz. Below the plane, we find the largest radial gradient to be ∂VR/∂R = -7.01 ± 0.61 km s-1 kpc-1, in agreement with recent studies. Above the plane, we find a similar gradient with ∂VR/∂R = -9.42 ± 1.77 km s-1 kpc-1. By comparing our results with previous studies, we find that the structure in Vz is strongly dependent on the adopted proper motions. Using the Galaxia Milky Way model, we demonstrate that distance uncertainties can create artificial wave-like patterns. In contrast to previous suggestions of a breathing mode seen in RAVE data, our results support a combination of bending and breathing modes, likely generated by a combination of external or internal and external mechanisms.

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published
subject
keywords
Galaxy: disc, Galaxy: kinematics and dynamics, Galaxy: structure
in
Monthly Notices of the Royal Astronomical Society
volume
475
issue
2
pages
18 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:85046094118
ISSN
0035-8711
DOI
10.1093/mnras/stx3342
language
English
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yes
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3f8e60ca-e36d-4cd0-949d-5ae9401b550d
date added to LUP
2018-05-14 15:53:39
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2018-05-29 11:38:48
@article{3f8e60ca-e36d-4cd0-949d-5ae9401b550d,
  abstract     = {<p>We use data from the Radial Velocity Experiment (RAVE) and the Tycho-Gaia astrometric solution (TGAS) catalogue to compute the velocity fields yielded by the radial (V<sub>R</sub>), azimuthal (Vϕ),and vertical (V<sub>z</sub>) components of associated Galactocentric velocity. We search in particular for variation in all three velocity components with distance above and below the disc midplane, as well as how each component of V<sub>z</sub> (line-of-sight and tangential velocity projections) modifies the obtained vertical structure. To study the dependence of velocity on proper motion and distance, we use two main samples: a RAVE sample including proper motions from the Tycho-2, PPMXL, and UCAC4 catalogues, and a RAVE-TGAS sample with inferred distances and proper motions from the TGAS and UCAC5 catalogues. In both samples, we identify asymmetries in V<sub>R</sub> and V<sub>z</sub>. Below the plane, we find the largest radial gradient to be ∂V<sub>R</sub>/∂R = -7.01 ± 0.61 km s<sup>-1</sup> kpc<sup>-1</sup>, in agreement with recent studies. Above the plane, we find a similar gradient with ∂V<sub>R</sub>/∂R = -9.42 ± 1.77 km s<sup>-1</sup> kpc<sup>-1</sup>. By comparing our results with previous studies, we find that the structure in V<sub>z</sub> is strongly dependent on the adopted proper motions. Using the Galaxia Milky Way model, we demonstrate that distance uncertainties can create artificial wave-like patterns. In contrast to previous suggestions of a breathing mode seen in RAVE data, our results support a combination of bending and breathing modes, likely generated by a combination of external or internal and external mechanisms.</p>},
  author       = {Carrillo, I. and Minchev, I. and Kordopatis, G. and Steinmetz, M. and Binney, J. and Anders, F. and Bienaymé, O. and Bland-Hawthorn, J. and Famaey, B. and Freeman, K. C. and Gilmore, G. and Gibson, B. K. and Grebel, E. K. and Helmi, A. and Just, A. and Kunder, A. and McMillan, P. and Monari, G. and Munari, U. and Navarro, J. and Parker, Q. A. and Reid, W. and Seabroke, G. and Sharma, S. and Siebert, A. and Watson, F. and Wojno, J. and Wyse, R. F.G. and Zwitter, T.},
  issn         = {0035-8711},
  keyword      = {Galaxy: disc,Galaxy: kinematics and dynamics,Galaxy: structure},
  language     = {eng},
  month        = {04},
  number       = {2},
  pages        = {2679--2696},
  publisher    = {Wiley-Blackwell},
  series       = {Monthly Notices of the Royal Astronomical Society},
  title        = {Is the Milky Way still breathing? RAVE-Gaia streaming motions},
  url          = {http://dx.doi.org/10.1093/mnras/stx3342},
  volume       = {475},
  year         = {2018},
}