Analysis of the spiral structure in a simulated galaxy

TL;DR

This paper investigates the impact of gaseous components on spiral structures in simulated galaxies, revealing that gas presence results in tighter spirals and a superposition of wave patterns with consistent velocities.

Contribution

It introduces a comparative simulation approach to analyze how gas influences spiral morphology and pattern velocities in galactic disks.

Findings

Gaseous component leads to tighter spiral arms.

Spiral pattern is a superposition of waves with constant pattern velocities.

Simulation results align with wave superposition theory.

Abstract

We analyze the spiral structure that results in a numerical simulation of a galactic disk with stellar and gaseous components evolving in a potential that includes an axisymmetric halo and bulge. We perform a second simulation without the gas component to observe how it affects the spiral structure in the disk. To quantify this, we use a Fourier analysis and obtain values for the pitch angle and the velocity of the self-excited spiral pattern of the disk. The results show a tighter spiral in the simulation with gaseous component. The spiral structure is consistent with a superposition of waves, each with a constant pattern velocity in given radial ranges.