Comparing dynamical effects of the central bar and the spiral arms in the solar neighborhood

TL;DR

This study compares the dynamical influences of the Galactic central bar and spiral arms on stellar motions in the solar neighborhood, using Gaia data and analytical models to identify resonances and their role in forming moving groups.

Contribution

It provides a detailed comparison of the effects of the Galactic bar and spiral arms on stellar dynamics, highlighting the spiral arms' better fit to observed moving groups.

Findings

Spiral arms model aligns better with observed moving groups.

Resonance locations correspond to main moving groups in the solar neighborhood.

Dynamical features like corotation and Lindblad resonances are identified.

Abstract

The dynamical effects on the stellar motion produced by the Galactic central bar and the spiral arms perturbations are investigated separately and compared. The stars from the Gaia DR3 catalog are selected in the region of observable completeness, which we estimate as $\sim$1 kpc from the Sun. We apply the 2D model of the Galactic potential consisting of three axisymmetric components, the disk, the bulge, and the dark matter halo, and two non-axisymmetric components, the central bar and the spiral arms. The stellar dynamics is studied using analytical and numerical techniques, such as Hamiltonian topology analysis, the construction of dynamical maps on the representative planes, dynamic spectra, and Poincar\'e sections. We identify the main dynamical features in the solar neighborhood (SNd), the corotation (CR) and Lindblad resonances (LRs). By assuming that the main moving groups (MGs) in the SNd originate from the resonances, we compare their locations, structures, and intensities with the theoretical predictions and provide a description of the process involved in the formation of the MGs. In addition, we explore parametric planes by adjusting the values of the pattern rotation speed $\Omega_{p}$ with the positions of the MGs, for both the spiral arms and bar models, and conclude that the spiral arms model shows better results when compared to those of the bar, under the hypothesis of the dynamical origin of MGs.