The Wobbly Galaxy : kinematics north and south with RAVE red-clump giants

By M. Williams, Matthias Steinmetz, J. Binney, A. Siebert, H. Enke, B. Famaey, I. Minchev, R. D. de Jong, C. Boeche, Kenneth C. Freeman and 16 more. 2013

205 citations recorded by the source corpus.

The RAdial Velocity Experiment survey, combined with proper motions and distance estimates, can be used to study in detail stellar kinematics in the extended solar neighbourhood (solar suburb). Using 72 365 red-clump stars, we examine the mean velocity components in 3D between 6 <R <10 kpc and -2 <Z <2 kpc, concentrating on north-south differences. Simple parametric fits to the (R, Z) trends for Vφ and the velocity dispersions are presented. We confirm the recently discovered gradient in mean Galactocentric radial velocity, VR, finding that the gradient is marked below the plane (δ/δR = -8 km s-1 kpc-1 for Z <0, vanishing to zero above the plane), with a Z gradient thus also present. The vertical velocity, VZ, also shows clear, large-amplitude (|VZ| = 17 km s-1) structure, with indications of a rarefaction-compression pattern, suggestive of wave-like behaviour. We perform a rigorous error analysis, tracing sources of both systematic and random errors. We confirm the north-south differences in VR and VZ along the line of sight, with the VR estimated independent of the proper motions. The complex three-dimensional structure of velocity space presents challenges for future modelling of the Galactic disc, with the Galactic bar, spiral arms and excitation of wave-like structures all probably playing a role.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/e1ad6d517f0f28eff505b45d73b5f881e55afecc

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Citations in the corpus

THE RADIAL VELOCITY EXPERIMENT (RAVE): FIFTH DATA RELEASE (2013, methodology): “For example, in recent years a wave-like pattern in the stellar velocity distribution was uncovered (Williams et al. 2013) and the total mass of the Milky Way was measured using the RAVE extreme-velocity stars (Piffl et al. 2014a), as was the local dark matter density (Bienaymé et al. 2014; Piffl…”
The GALAH survey and Gaia DR2: dissecting the stellar disc’s phase space by age, action, chemistry, and location (2018, background): “These also manifest as kinematic (Widrow et al. 2012; Williams et al. 2013; Carlin et al. 2013) and density asymmetries (Yanny & Gardner 2013; Slater et al. 2014; Xu et al. 2015) above and below the Galactic plane.”
The Lives of Stars: Insights from the TGAS–RAVE–LAMOST Data Set (2018, background): “VR (not shown) does not change significantly with age, the average being -3.9 km s−1, comparable to Williams et al. (2013).”
THE APOGEE RED-CLUMP CATALOG: PRECISE DISTANCES, VELOCITIES, AND HIGH-RESOLUTION ELEMENTAL ABUNDANCES OVER A LARGE AREA OF THE MILKY WAY'S DISK (2014, methodology): “This contamination can be compared, for example, to the selection technique used by Williams et al. (2013), which consists of the simpler cuts 0.55 ≤ (J −K)0 ≤ 0.8 and 1.8 ≤ log g ≤ 3.0.”
The local dark matter density (2014, background): “These same surveys have recently found evidence for vertical density waves in the Milky Way disc (Widrow et al., 2012; Williams et al., 2013; Yanny & Gardner, 2013), perhaps caused by the recent Sagittarius dwarf merger (Gómez et al., 2013).”
RINGS AND RADIAL WAVES IN THE DISK OF THE MILKY WAY (2015, methodology): “Velocity substructure in the disk that could be caused by a wavelike perturbation of the disk was also seen by Williams et al. (2013) in data from the RAdial Velocity Experiment (Steinmetz et al. 2006)and by Carlin et al. (2013) in data from the Large Area Multi-Object Spectroscopic Telescope…”
The Galaxy in Context: Structural, Kinematic, and Integrated Properties (2016, background): “One reason for this may arise from local kinematic substructure or any systematic streaming motion vstr in the Sun’s vicinity (Dehnen 2000, Siebert et al. 2011, Williams et al. 2013, Antoja et al. 2014).”
The Milky Way's rotation curve out to 100 kpc and its constraint on the Galactic mass distribution (2016, methodology): “8.5 kpc (Siebert et al. 2011; Williams et al. 2013), suggest that the value of mean radial motion oscillates withR.”
Constraining the Milky Way assembly history with Galactic Archaeology (2016, background): “Gómez et al. (2013) showed that just such a disturbance from the Sagittarius dwarf galaxy can explain the recent discovery of vertical waves near the Sun in SEGUE (Widrow et al., 2012) and RAVE (Williams et al., 2013).”
The GALAH survey: observational overview and Gaia DR1 companion (2016, background): “(2016) large comparison set for GALAH radial velocities, and will enable detailed followup and extension of important RAVE studies of Galactic dynamics and structure (e.g., Williams et al. 2013; Antoja et al. 2012, Siebert et al. 2012; Ruchti et al. 2011).”
Constraining the Galaxy's dark halo with RAVE stars (2014, methodology): “The first two points include the approximation that the Galactic disc is smooth and axisymmetric, so the flows induced by spiral waves that have been detected by RAVE (Siebert et al. 2012; Williams et al. 2013) and in simulations (Debattista 2014; Faure, Siebert & Famaey 2014) are neglected.”
Galaxy Masses: A Review (2013, result): “This result has also been observed in the RAVE survey (Williams et al. 2013).”
The influence of Sagittarius and the Large Magellanic Cloud on the stellar disc of the Milky Way Galaxy (2017, methodology): “…asymmetries in physical space (Widrow et al. 2012) but also the associated vertical motions of the disc which were also observed by RAVE and LAMOST (Williams et al. 2013; Carlin et al. 2013), GASS/Monoceros Ring (Newberg et al. 2002; Slater et al. 2014; Morganson et al. 2016), but also the…”