Manifold-driven spirals in N-body barred galaxy simulations

TL;DR

This paper provides evidence that spiral arms in a barred galaxy simulation are driven by manifolds, showing how their shape and extent evolve with the galaxy's bar properties, leading to significant disc growth.

Contribution

It demonstrates manifold-driven spiral arms in N-body simulations and links their properties to the evolution of the galaxy's bar and pattern speed.

Findings

Spiral arms follow trajectories consistent with manifold-driven dynamics.

The shape and radial extent of arms change with bar strength and pattern speed.

Disc size increases by up to 50% over approximately one billion years.

Abstract

We discuss the properties of spiral arms in a N-body simulation of a barred galaxy and present evidence that these are manifold-driven. The strongest evidence comes from following the trajectories of individual particles. Indeed, these move along the arms while spreading out a little. In the neighbourhood of the Lagrangian points they follow a variety of paths, as expected by manifold-driven trajectories. Further evidence comes from the properties of the arms themselves, such as their shape and growth pattern. The shape of the manifold arms changes considerably with time, as expected from the changes in the bar strength and pattern speed. In particular, the radial extent of the arms increases with time, thus bringing about a considerable increase of the disc size, by as much as ~50% in about a Gyr.