The vertical effects of disc non-axisymmetries from perturbation theory: the case of the Galactic bar

Abstract

Evidence for non-zero mean stellar velocities in the direction perpendicular to the Galactic plane has been accumulating from various recent large spectroscopic surveys. Previous analytical and numerical work has shown that a "breathing mode" of the Galactic disc, similar to what is observed in the Solar vicinity, can be the natural consequence of a non-axisymmetric internal perturbation of the disc. Here we provide a general analytical framework, in the context of perturbation theory, allowing us to compute the vertical bulk motions generated by a single internal perturber (bar or spiral pattern). In the case of the Galactic bar, we show that these analytically predicted bulk motions are well in line with the outcome of a numerical simulation. The mean vertical motions induced by the Milky Way bar are small (mean velocity of less than 1 km/sec) and cannot be responsible alone for the observed breathing mode, but they are existing. Our analytical treatment is valid close to the plane for all the non-axisymmetric perturbations of the disc that can be described by small-amplitude Fourier modes. Further work should study how the coupling of multiple internal perturbers and external perturbers is affecting the present analytical results.

arXiv comment9 pages, 6 figures, accepted for publication in MNRAS. Error corrected, figures updated, added term in Eqs. 10 and 18 with no consequences on the conclusions

References in corpus (26)

• The Effect of the Outer Lindblad Resonance of the Galactic Bar on the Local Stellar Velocity Distribution
• The Local Dark Matter Density
• Local kinematics of K and M giants from Coravel/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters
• The Distribution of Nearby Stars in Velocity Space Inferred from Hipparcos Data
• Galactoseismology: Discovery of Vertical Waves in the Galactic Disk
• The wobbly Galaxy: kinematics north and south with RAVE red clump giants
• Rings and Radial Waves in the Disk of the Milky Way
• Vertical density waves in the Milky Way disc induced by the Sagittarius Dwarf Galaxy
• Bending and Breathing Modes of the Galactic Disk
• Constraints on the Galactic Bar from the Hercules stream as traced with RAVE across the Galaxy
• Substructure in bulk velocities of Milky Way disk stars
• Radial and vertical flows induced by galactic spiral arms: likely contributors to our "wobbly Galaxy''
• Origin and evolution of moving groups I. Characterization in the observational kinematic-age-metallicity space
• The distribution of nearby stars in phase space mapped by Hipparcos III. Clustering and streaming among A-F type stars
• The properties of the local spiral arms from RAVE data: two-dimensional density wave approach
• Analytical Expressions for Spiral Arm Gravitational Potential and Density
• Weighing the local dark matter with RAVE red clump stars
• Detection of a radial velocity gradient in the extended local disc with RAVE
• The Stellar Number Density Distribution in the Local Solar Neighborhood is North-South Asymmetric
• The power spectrum of the Milky Way: Velocity fluctuations in the Galactic disk
• Vertical distribution of Galactic disk stars : II. The surface mass density in the Galactic plane
• Detecting Dark Matter Substructures around the Milky Way with Gaia
• The Vertical Structure and Kinematics of Grand Design Spirals
• Kinematic Signature of a Rotating Bar Near a Resonance
• The Galactic bar and the large scale velocity gradients in the Galactic disk
• Vertical Oscillations of Fluid and Stellar Disks

Cited by in corpus (42)

• The Influence of Sagittarius and the Large Magellanic Cloud on the Milky Way Galaxy
• Vertical disc heating in Milky Way-sized galaxies in a cosmological context
• Response of the Milky Way's disc to the Large Magellanic Cloud in a first infall scenario
• The effects of bar-spiral coupling on stellar kinematics in the Galaxy
• The Canada-France Imaging Survey: First results from the u-band component
• Constraining a Thin Dark Matter Disk with Gaia
• A fully cosmological model of a Monoceros-like ring
• Modelling the Galactic disc: perturbed distribution functions in the presence of spiral arms
• Excitation of coupled stellar motions in the Galactic Disk by orbiting satellites
• Emergence of the Gaia Phase Space Spirals from Bending Waves
• Bending Waves in the Milky Way's disc from halo substructure
• Multiple phase spirals suggest multiple origins in Gaia DR3
• Is the Milky Way still breathing? RAVE-Gaia streaming motions
• Kinematics with Gaia DR2: The Force of a Dwarf
• 3D Asymmetrical motions of the Galactic outer disk with LAMOST K giant stars
• Staying away from the bar: the local dynamical signature of slow and fast bars in the Milky Way
• Mapping the Galactic disk with the LAMOST and Gaia Red clump sample. II. 3D asymmetrical kinematics of mono-age populations in the disk between 6$-14$ \,kpc
• Phase Wrapping of Epicyclic Perturbations in the Wobbly Galaxy
• Exploring the pertubed Milky Way disk and the substructures of the outer disk
• Spontaneous generation of bending waves in isolated Milky Way-like discs
• Milky Way Tomography with K and M Dwarf Stars: the Vertical Structure of the Galactic Disk
• Dissecting the Phase Space Snail Shell
• Did Sgr cause the vertical waves in the solar neighbourhood?
• Distribution functions for resonantly trapped orbits in the Galactic disc
• Vertical Phase Mixing across the Galactic Disk
• Timing the Milky Way bar formation and the accompanying radial migration episode
• The kinematic signature of the Galactic warp in Gaia DR1 - I. The Hipparcos subsample
• Mapping Milky Way disk perturbations in stellar number density and vertical velocity using Gaia DR3
• Excitation of vertical breathing motion in disc galaxies by tidally-induced spirals in fly-by interactions
• Swing Amplification and the Gaia Phase Spirals
• Age dissection of the vertical breathing motions in Gaia DR2: evidence for spiral driving
• Gaia DR3 features of the phase spiral and its possible relation to internal perturbations
• A Map of the Local Velocity Substructure in the Milky Way Disk
• The North/South Asymmetry of the Galaxy: Possible Connection to the Vertical Phase Space Snail
• Growing Local arm inferred by the breathing motion
• Asymmetric metallicity patterns in the stellar velocity space with RAVE
• 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
• Collisionless Boltzmann equation approach for the study of stellar discs within barred galaxies
• Optimal Emergency Frequency Control Based on Coordinated Droop in Multi-Infeed Hybrid AC-DC System
• Quadrupole signature as a kinematic diagnostic to constrain bar properties : implications for the Milky Way