Age dissection of the vertical breathing motions in Gaia DR2: evidence for spiral driving

Abstract

Gaia DR2 has revealed breathing motions in the Milky Way, with stars on both sides of the Galactic mid-plane moving coherently towards or away from it. The generating mechanism of these breathing motions is thought to be spiral density waves. Here we test this hypothesis. Using a self-consistent, high-resolution simulation with star formation, and which hosts prominent spirals, we first study the signatures of breathing motions excited by spirals. In the model, the breathing motions induced by the spiral structure have an increasing amplitude with distance from the mid-plane, pointing to an internal cause for them. We then show that, at fixed height, the breathing motion amplitude decreases with age. Next, we investigate the signature of the breathing motions in the Gaia DR2 dataset. We demonstrate that, at the location with a consistently large breathing motion, the corresponding amplitude increases monotonically with distance from the mid-plane, in agreement with the model. Furthermore, we show that at the same location, the breathing motion amplitude decreases with age, again similar to what we find in the model. This strengthens the case that the observed breathing motions are driven by spiral density waves.

17 pages, 19 figures, accepted for publication in MNRAS

References in corpus (14)

• The Gaia mission
• galpy: A Python Library for Galactic Dynamics
• The mass distribution and gravitational potential of the Milky Way
• Star Formation and Feedback in Smoothed Particle Hydrodynamic Simulations--I. Isolated Galaxies
• Riding the Spiral Waves: Implications of Stellar Migration for the Properties of Galactic Disks
• Dawes Review 4: Spiral Structures in Disc Galaxies
• Distances and parallax bias in Gaia DR2
• Bending and Breathing Modes of the Galactic Disk
• Radial and vertical flows induced by galactic spiral arms: likely contributors to our "wobbly Galaxy''
• Galaxy Zoo: Morphological Classifications for 120,000 Galaxies in HST Legacy Imaging
• The Vertical Structure and Kinematics of Grand Design Spirals
• The vertical effects of disc non-axisymmetries from perturbation theory: the case of the Galactic bar
• A multi-wavelength study of spiral structure in galaxies. I. General characteristics in the optical
• Manifold spirals in barred galaxies with multiple pattern speeds

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• Growing Local arm inferred by the breathing motion
• The pattern speeds of vertical breathing waves
• Quantifying the influence of bars on action-based dynamical modelling of disc galaxies
• Chemodynamical Ages of Small-Scale Kinematic Structures of the Galactic Disc in the Solar Neighborhood from ~250,000 K and M Dwarfs
• Two-point correlation function studies for the Milky Way: discovery of spatial clustering from disk excitations and substructure
• Dark matter spiral arms in Milky Way-like halos
• A Wave-Corrected Assessment of the Local Midplane
• Dynamical interplay of disc thickness and the interstellar gas: implication for the longevity of spiral density waves
• Correlation between the two-armed $V_R$ spiral in the $Z$--$V_Z$ plane and moving groups
• Phase spirals induced by the gas warp