Radial migration in a stellar galactic disc with thick components

TL;DR

This study investigates how stellar migration occurs in a galaxy with both thin and thick disc components, revealing that stars of all components can be trapped at the bar's corotation and that migration is influenced by bar dynamics.

Contribution

It provides new insights into the effects of a strong bar and spiral arms on stellar migration across different galactic disc components.

Findings

Migration amplitude is similar for thin and thick components.

Stars far from their initial radius are mainly affected by blurring.

Stars trapped at corotation can be churned outwards as the bar slows down.

Abstract

We study how migration affects stars of a galaxy with a thin stellar disc and thicker stellar components. The simulated galaxy has a strong bar and lasting spiral arms. We find that the amplitude of the churning (change in angular momentum) is similar for thin and thick components, and of limited amplitude, and that stars of all components can be trapped at the corotation of the bar. At the exception of those stars trapped at the corotation, we find that stars that are far from their initial guiding radius are more likely so due to blurring rather than churning effects. We compare the simulation to orbits integration with a fixed gravitational potential rotating at a constant speed. In the latter case, stars trapped at corotation are churned periodically outside and inside the corotation radius, with a zero net average. However, as the bar speed of the simulated galaxy decreases and its corotation radius increases, stars trapped at corotation for several Gyrs can be churned outwards on average. We study the location of extreme migrators (stars experimenting the largest churning) and find that extreme migrators come from regions on the leading side of the effective potential local maxima.