Polygonal Structures in the Gaseous Disk: Numerical Simulations

TL;DR

This paper presents numerical simulations of gaseous disks influenced by stellar spiral density waves, analyzing the formation of straightened spiral arm segments and comparing results with observed galaxy structures.

Contribution

It introduces comprehensive 2D and 3D hydrodynamic simulations exploring conditions for spiral arm segment formation in gaseous disks, aligning with observational data.

Findings

Rows are nonstationary phenomena in simulations.

Simulations match observed average segment angles (~120°).

Good agreement between models and galaxy observations.

Abstract

The results of numerical simulations of a gaseous disk in the potential of a stellar spiral density wave are presented. The conditions under which straightened spiral arm segments (rows) form in the gas component are studied. These features of the spiral structure were identified in a series of works by A.D. Chernin with coauthors. Gas-dynamic simulations have been performed for a wide range of model parameters: the pitch angle of the spiral pattern, the amplitude of the stellar spiral density wave, the disk rotation speed, and the temperature of the gas component. The results of 2D- and 3D-disk simulations are compared. The rows in the numerical simulations are shown to be an essentially nonstationary phenomenon. A statistical analysis of the distribution of geometric parameters for spiral patterns with rows in the observed galaxies and the constructed hydrodynamic models shows good agreement. In particular, the numerical simulations and observations of galaxies give $<{\alpha}>\simeq 120^\circ$ for the average angles between straight segments.