From ridges in the velocity distribution to wiggles in the rotation curve

Abstract

Recently, the Gaia data release 2 (DR2) showed us the richness in the kinematics of the Milky Way disk. Of particular interest is the presence of ridges covering the stellar velocity distribution, $V_{\varphi }-R$; as shown by others, it is likely that these ridges are the signature of phase mixing, transient spirals, or the bar. Here, with a Galactic model containing both: bar and spirals, we found the same pattern of ridges extending from the inner to the outer disk. Interestingly, ridges in the $V_{\varphi }-R$ plane correlate extremely well with wiggles in the computed rotation curve (RC). Hence, although the DR2 reveals (for the first time) such substructures in a wide spatial coverage, we notice that we have always seen such pattern of ridges, but projected into the form of wiggles in the RC. The separation and amplitude of the wiggles strongly depend on the extension and layout of ridges in the $V_{\varphi }-R$ plane. This means that within the RC are encoded the kinematic state of the disk as well as information about the bar and spiral arms. The amplitude of the wiggles suggests that similar features currently observable in external galaxies RCs have similar origins, triggered by spirals and bars.

5 pages, 5 figures, deeper analysis on the ridges' resonant origin. Accepted for publication in MNRAS Letters

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Cited by in corpus (14)

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• Galactic seismology: the evolving "phase spiral" after the Sagittarius dwarf impact
• Gaia Early Data Release 3: The Galactic anticentre
• Signatures of resonance and phase mixing in the Galactic disc
• The Rotation Curve, Mass Distribution and Dark Matter Content of the Milky Way from Classical Cepheids
• Hic sunt dracones: Cartography of the Milky Way spiral arms and bar resonances with Gaia Data Release 2
• Chemo-kinematics of the Milky Way spiral arms and bar resonances: connection to ridges and moving groups in the Solar vicinity
• Exploring the origin of moving groups and diagonal ridges by simulations of stellar orbits and birthplaces
• Kinematic footprint of the Milky Way spiral arms in Gaia EDR3
• A new resonance-like feature in the outer disc of the Milky Way
• The imprint of arms and bars on rotation curves: in-plane and off-plane
• On the Migration Origin of the Hercules Moving Group with GAIA, LAMOST, APOGEE, and GALAH Surveys
• Kinematic-Chemical analysis and Time tagging for the Diagonal Ridge Structure of the Galactic Outer Disk with LAMOST Red Giant Branch Stars
• Wrinkles in Time. II. Stellar Age Trends in Kinematic Signatures from Transient Spiral Structure