Stellar diffusion in barred spiral galaxies

TL;DR

This paper empirically investigates how stars diffuse radially in barred spiral galaxies, showing that diffusion varies with disk stability and bar activity, impacting galaxy evolution models.

Contribution

It provides a detailed analysis of stellar diffusion in barred galaxies using N-body simulations, highlighting the influence of bar strength and disk stability on diffusion processes.

Findings

Diffusion is larger in marginally stable disks with Q_T ~ 1.

Hot disks (Q_T > 1) exhibit reduced stellar diffusion.

Bar activity causes recurrent star movement across the disk.

Abstract

We characterize empirically the radial diffusion of stars in the plane of a typical barred disk galaxy by calculating the local spatial diffusion coefficient and diffusion time-scale for bulge-disk-halo N-body self-consistent systems which initially differ in the Safronov-Toomre-Q_T parameter. We find different diffusion scenarios that depend on the bar strength and on the degree of instability of the disk. Marginally stable disks, with Q_T \sim 1, have two families of bar orbits with different values of angular momentum and energy, which determine a large diffusion in the corotation region. In hot disks, Q_T> 1, stellar diffusion is reduced with respect to the case of marginally stable disks. In cold models, we find that spatial diffusion is not constant in time and strongly depends on the activity of the bar, which can move stars all over the disk recurrently. We conclude that to realistically study the impact of radial migration on the chemical evolution modeling of the Milky Way the role of the bar has to be taken into account.