English

Multiple phase spirals suggest multiple origins in Gaia DR3

Astrophysics of Galaxies 2022-07-28 v2

Abstract

{\it Gaia} Data Release 2 (DR2) revealed that the Milky Way contains significant indications of departures from equilibrium in the form of asymmetric features in the phase space density of stars in the Solar neighborhood. One such feature is the zz--vzv_z phase spiral, interpreted as the response of the disk to the influence of a perturbation perpendicular to the disk plane, which could be external (e.g., a satellite) or internal (e.g., the bar or spiral arms). In this work we use {\it Gaia} DR3 to dissect the phase spiral by dividing the local data set into groups with similar azimuthal actions, JϕJ_\phi, and conjugate angles, θϕ\theta_\phi, which selects stars on similar orbits and at similar orbital phases, thus having experienced similar perturbations in the past. These divisions allow us to explore areas of the Galactic disk larger than the surveyed region. The separation improves the clarity of the zz--vzv_z phase spiral and exposes changes to its morphology across the different action-angle groups. In particular, we discover a transition to two armed `breathing spirals' in the inner Milky Way. We conclude that the local data contains signatures of not one, but multiple perturbations with the prospect to use their distinct properties to infer the properties of the interactions that caused them.

Keywords

Cite

@article{arxiv.2206.06125,
  title  = {Multiple phase spirals suggest multiple origins in Gaia DR3},
  author = {Jason A. S. Hunt and Adrian M. Price-Whelan and Kathryn V. Johnston and Elise Darragh-Ford},
  journal= {arXiv preprint arXiv:2206.06125},
  year   = {2022}
}

Comments

5 pages, 3 figures, accepted in MNRAS letters

R2 v1 2026-06-24T11:48:50.939Z