Evidence in favour of density wave theory through star formation history maps and spatially resolved stellar clusters

TL;DR

This study provides evidence supporting the Stationary Density Wave Theory by analyzing star formation history maps and stellar cluster ages in spiral galaxies, revealing age gradients consistent with the theory.

Contribution

The paper introduces a method combining SFH maps and spatially resolved stellar clusters to test density wave theory, demonstrating age gradients across spiral arms.

Findings

Gradual decrease in pitch angles with increasing stellar age

Age gradients observed across spiral arms consistent with stationary density wave predictions

Use of SFH maps and stellar cluster offsets as effective tools for testing spiral arm theories

Abstract

Stationary Density Wave Theory predicts the existence of an age gradient across the spiral arms with a phase crossing at the co-rotation radius. Using star formation history (SFH) maps of 12 nearby spiral galaxies derived from \textsc{LIGHTNING} \citep{Eufracio:2017}, a spectral energy distribution (SED) fitting procedure, and by using \textsc{Spirality} \citep{Shield:2015} a \textsc{MATLAB}-based code which plots synthetic spiral arms over \textsc{FITS} images, we have found a gradual decrement in pitch angles with increasing age, thus providing us with evidence in favour of the Stationary Density Wave Theory. We have also used azimuthal offsets of spatially resolved stellar clusters in 3 LEGUS galaxies to observe age trends.