Gaia DR3 features of the phase spiral and its possible relation to internal perturbations

Abstract

Disc stars from the Gaia DR3 RVS catalogue are selected to explore the phase spiral as a function of position in the Galaxy. The data reveal a two-armed phase spiral pattern in the local $z-v_z$ plane inside the solar radius, which appears clearly when colour-coded by $⟨v_R⟩(z,v_z)$: this is characteristic of a breathing mode that can in principle be produced by in-plane non-axisymmetric perturbations. We note the phase spiral pattern becomes single armed outside the solar radius. When a realistic analytic model with an axisymmetric background potential plus a steadily rotating bar and 2-armed spiral arms as perturbation is used to perform particle test integrations, the pseudo stars get a prominent spiral pattern in the $⟨v_R⟩$ map in the $x-y$ plane. Additionally, clear breathing mode evidence at a few ${\mathrm{kms}}^{-1}$ level can be seen in the $⟨v_z⟩$ map on the $x-z$ plane, confirming that such breathing modes are non-negligible in the joint presence of a bar and spiral arms. However, no phase-spiral is perceptible in the $(z,v_z)$ plane. When an initial vertical perturbation is added to all pseudo stars to carry out the simulation, the one-armed phase spirals can clearly be seen 500~Myr after the perturbation and gradually disappear inside-out. Finally, we show as a proof of concept how a toy model of a time-varying non-axisymmetric in-plane perturbation with varying amplitude and pattern speed can produce a strong two-armed phase-spiral. We conclude a time-varying strong internal perturbation together with an external vertical perturbation could perhaps explain the transition between the two-armed and one-armed phase-spirals around the Solar radius.

14 pages, 15 figures, accepted by MNRAS

References in corpus (19)

• The Gaia mission
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• The Structure of the Milky Way's Bar Outside the Bulge
• Radial and vertical flows induced by galactic spiral arms: likely contributors to our "wobbly Galaxy''
• The Rotation Curve, Mass Distribution and Dark Matter Content of the Milky Way from Classical Cepheids
• Multiple phase spirals suggest multiple origins in Gaia DR3
• The stellar mass distribution of the Milky Way's bar: an analytic model
• The vertical effects of disc non-axisymmetries from perturbation theory: the case of the Galactic bar
• Self-consistent models of our Galaxy
• The phase spiral in Gaia DR3
• The origin and fate of the Gaia phase-space snail
• The Stellar Distribution Function and Local Vertical Potential from Gaia DR2
• Vertical motion in the Galactic disc: unwinding the Snail
• An ever-present $Gaia$ snail shell triggered by a dark matter wake
• A Comprehensive Perturbative Formalism for Phase-Mixing in Perturbed Disks. I. Phase spirals in an Infinite, Isothermal Slab
• Weighing the Galactic disk using phase-space spirals III. Probing distant regions of the disk using the Gaia EDR3 proper motion sample
• Swing Amplification and the Gaia Phase Spirals
• Our Galaxy's youngest disc
• $\text{ESCARGOT}$: Mapping Vertical Phase Spiral Characteristics Throughout the Real and Simulated Milky Way

Cited by in corpus (11)

• Ripples spreading across the Galactic disc. Interplay of direct and indirect effects of the Sagittarius dwarf impact
• Growing Local arm inferred by the breathing motion
• Exploring the impact of a rapidly decelerating bar on transforming bulge orbits into disc-like orbits
• Could very low-metallicity stars with rotation-dominated orbits have been shepherded by the bar?
• Limitations and rotation of the two-armed phase spiral in the Milky Way stellar disc
• A non-axisymmetric potential for the Milky Way disk
• First large scale spatial and velocity patterns of local metal-rich stars in the Milky Way
• Phase spirals induced by the gas warp
• Correlation between the two-armed $V_R$ spiral in the $Z$--$V_Z$ plane and moving groups
• The multiple corrugations in the Galactic disk derived from the LAMOST and Gaia survey data
• Wrinkles in Time. II. Stellar Age Trends in Kinematic Signatures from Transient Spiral Structure