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Is the Milky Way still breathing? RAVEā€“Gaia streaming motions

Published version
Peer-reviewed

Type

Article

Change log

Authors

Carrillo, I 
Minchev, I 
Kordopatis, G 
Steinmetz, M 
Binney, J 

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 (VĻ•),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 mid-plane, 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 RAVEā€“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 āˆ‚VR/āˆ‚R = āˆ’7.01 Ā± 0.61ā€‰kmā€‰sāˆ’1ā€‰kpcāˆ’1, in agreement with recent studies. Above the plane, we find a similar gradient with āˆ‚VR/āˆ‚R = āˆ’9.42 Ā± 1.77ā€‰kmā€‰sāˆ’1ā€‰kpcāˆ’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.

Description

Keywords

Galaxy: disc, Galaxy: kinematics and dynamics, Galaxy: structure

Journal Title

Monthly Notices of the Royal Astronomical Society

Conference Name

Journal ISSN

1365-2966
1365-2966

Volume Title

475

Publisher

Oxford University Press
Sponsorship
Leverhulme Trust (RPG-2012-541)
European Research Council (320360)
Funding for RAVE has been provided by the Australian Astronomical Observatory; the Leibniz-Institut fĆ¼r Astrophysik Potsdam (AIP); the Australian National University; the Australian Research Council; the French National Research Agency; the German Research Foundation (SPP 1177 and SFB 881); the European Research Council (ERC-StG 240271 Galactica); the Istituto Nazionale di Astrofisica at Padova; the Johns Hopkins University; the National Science Foundation of the USA (AST-0908326); the W. M. Keck foundation; the Macquarie University; the Netherlands Research School for Astronomy; the Natural Sciences and Engineering Research Council of Canada; the Slovenian Research Agency (research core funding No. P1-0188); the Swiss National Science Foundation; the Science & Technology Facilities Council of the UK; Opticon; Strasbourg Observatory; and the Universities of Groningen, Heidelberg, and Sydney. The RAVE website is https://www.rave-survey.org. EKG acknowledges support by Sonderforschungsbereich ā€˜The Milky Way Systemā€™ (SFB 881) of the German Research Foundation (DFG), particularly through subproject A5.