Revealing the spiral arms through radial migration and the shape of the Metallicity Distribution Function

TL;DR

This study uses simulations to show how spiral arms and the Galactic bar influence the metallicity distribution function across the Milky Way, revealing the impact of radial migration on galactic structure.

Contribution

It demonstrates that spiral arms primarily shape the MDF in outer regions, providing a new way to infer spiral arm properties from metallicity data.

Findings

Spiral arms imprint their signature on the MDF in the outer disc.

The bar influences the MDF mainly in the inner disc.

The Galactic potential significantly affects the MDF shape.

Abstract

Recent observations show that the Milky Way's metallicity distribution function (MDF) changes its shape as a function of radius. This new evidence of radial migration within the stellar disc sets additional constraints on Galactic models. By performing controlled test particle simulations in a very detailed, observationally motivated model of the Milky Way, we demonstrate that, in the inner region of the disc, the MDF is shaped by the joint action of the bar and spiral arms, while at outer radii the MDF is mainly shaped by the spiral arms. We show that the spiral arms are able to imprint their signature in the radial migration, shaping the MDF in the outskirts of the Galactic disc with a minimal participation of the bar. Conversely, this work has the potential to characterise some structural and dynamical parameters of the spiral arms based on radial migration and the shape of the MDF. Finally, the resemblance obtained with this approximation to the MDF curves of the Galaxy as seen by APOGEE, show that a fundamental factor influencing their shape is the Galactic potential.