Investigations of dust heating in M81, M83, and NGC 2403 with the Herschel Space Observatory

TL;DR

This study analyzes how dust heating in three nearby spiral galaxies is influenced by star formation and stellar populations, revealing that different infrared wavelengths trace distinct dust components and heating sources.

Contribution

It provides new insights into the sources of dust heating at various infrared wavelengths, informing models of galaxy spectral energy distributions and star formation tracing.

Findings

70/160 micron ratios are influenced by star forming regions

250/350 and 350/500 micron ratios are affected by total stellar light

Far-infrared emission at >250 microns originates from colder dust less affected by star formation

Abstract

We use Spitzer Space Telescope and Herschel Space Observatory far-infrared data along with ground-based optical and near-infrared data to understand how dust heating in the nearby face-on spiral galaxies M81, M83, and NGC 2403 is affected by the starlight from all stars and by the radiation from star forming regions. We find that 70/160 micron surface brightness ratios tend to be more strongly influenced by star forming regions. However, the 250/350 micron and 350/500 micron surface brightness ratios are more strongly affected by the light from the total stellar populations, suggesting that the dust emission at >250 microns originates predominantly from a component that is colder than the dust seen at <160 microns and that is relatively unaffected by star formation activity. We conclude by discussing the implications of this for modelling the spectral energy distributions of both nearby and more distant galaxies and for using far-infrared dust emission to trace star formation.