Age distributions of star clusters in spiral and barred galaxies as a test for theories of spiral structure

TL;DR

This paper compares different models of spiral galaxy structure by analyzing how the age distribution of star clusters varies spatially, proposing that observations of these distributions can distinguish between the underlying spiral formation mechanisms.

Contribution

It introduces a method to use star cluster age distributions as a diagnostic tool to test and differentiate models of spiral structure in galaxies.

Findings

Spatial distributions of star clusters vary significantly across models.

Age-dated cluster locations can discriminate between spiral structure theories.

Proposes observational approach for testing spiral formation mechanisms.

Abstract

We consider models of gas flow in spiral galaxies in which the spiral structure has been excited by various possible mechanisms: a global steady density wave, self-gravity of the stellar disc and an external tidal interaction, as well as the case of a galaxy with a central rotating bar. In each model we estimate in a simple manner the likely current positions of star clusters of a variety of ages, ranging from ~ 2 Myr to around 130 Myr, depending on the model. We find that the spatial distribution of cluster of different ages varies markedly depending on the model, and propose that observations of the locations of age-dated stellar clusters is a possible discriminant between excitation mechanisms for spiral structure in an individual galaxy.