Cold Dust Content of Nearby Galaxies 01/01/2025

Earth and Space Sciences

Star-formation takes place in the cold dense molecular clouds, which also harbour the coldest dust grains present in star-forming galaxies. The emission from these very cold dust grains is challenging to detect alongside the overpowering emission from the warmer dust grains and the contamination from thermal and non-thermal radio emission at millimeter/sub-millimeter wavelengths. In this work, we looked at the multi-wavelength emission from four nearby star-forming spiral galaxies to search for signatures of these very cold dust grains and also quantify the very cold dust content. We do this by constructing their Spectral Energy Distributions (SEDs) across a vast wavelength range, extending from ultraviolet to radio frequencies, by combining observations from 12 different instruments/telescopes. These SEDs have information about various physical processes taking place in the galaxy embedded in them. We modelled the SEDs using a tool called CIGALE (Code Investigating GALaxy Emission) to extract various physical parameters of the galaxy and estimate the total and very cold dust components of the galaxies in our sample. We found hints of very cold dust in two of the targets, NGC 7496 and NGC 7590, where the very cold dust accounts for nearly half of the total dust content. The results for one of the galaxies in the sample, NGC 7590, are shown in the figure below.

Caption: Panels have titles that are self-explanatory.