Variation in the dust spectral index across M33

TL;DR

This study examines how the dust spectral index varies across the galaxy M33 using Herschel data, revealing higher values in the central regions and correlations with star formation indicators.

Contribution

It introduces an iteration method with single and two-component models to analyze dust spectral index variations at high spatial resolution in M33.

Findings

Higher dust spectral index in the galaxy's center

Positive correlation between spectral index and star formation tracers

Two-component model better constrains physical parameters

Abstract

Using the Herschel PACS and SPIRE FIR/submm data, we investigate variations in the dust spectral index $\beta$ in the nearby spiral galaxy M33 at a linear resolution of 160 pc. We use an iteration method in two different approaches, single and two-component modified black body models. In both approaches, $\beta$ is higher in the central disk than in the outer disk similar to the dust temperature. There is a positive correlation between $\beta$ and Halpha as well as with the molecular gas traced by CO(2-1). A Monte-Carlo simulation shows that the physical parameters are better constrained when using the two-component model.