Modeling of Spiral Structure in a Multi-Component Milky~Way-Like Galaxy

TL;DR

This study models a Milky Way-like galaxy using multi-component equilibrium models and simulations, revealing bar and spiral structures that persist for several billion years and depend on galaxy density profiles.

Contribution

It introduces a detailed multi-component galaxy model and demonstrates how bar and spiral structures form and evolve, influenced by density distribution and bulge presence.

Findings

A central bar forms after ~1 Gyr and persists for at least 3 Gyr.

Spiral patterns are multi-armed, consisting of m=2, 3, and 4 arms.

Bar formation is suppressed if the disk's radial scale length exceeds 2.6 kpc.

Abstract

Using recent observational data, we construct a set of multi-component equilibrium models of the disk of a Milky Way-like galaxy. The disk dynamics are studied using collisionless-gaseous numerical simulations, based on the joined integration of the equations of motion for the collision-less particles using direct integration of gravitational interaction and the gaseous SPH-particles. We find that after approximately one Gyr, a prominent central bar is formed having a semi-axis length of about three kpc, together with a multi-armed spiral pattern represented by a superposition of $m=$ 2-, 3-, and 4-armed spirals. The spiral structure and the bar exist for at least 3 Gyr in our simulations. The existence of the Milky Way bar imposes limitations on the density distributions in the subsystems of the Milky Way galaxy. We find that a bar does not form if the radial scale length of the density distribution in the disk exceeds 2.6 kpc. As expected, the bar formation is also suppressed by a compact massive stellar bulge. We also demonstrate that the maximum value in the rotation curve of the disk of the Milky Way galaxy, as found in its central regions, is explained by non-circular motion due to the presence of a bar and its orientation relative to an observer.