$\textit{Herschel}$ Photometric Observations of $\mathrm{L{\small{ITTLE}}}$ $\mathrm{T{\small{HINGS}}}$ Dwarf Galaxies

TL;DR

This study provides far-infrared photometry of low-metallicity dwarf galaxies, revealing their low dust content, cooler dust temperatures, and high dust destruction rates, contributing to understanding dust evolution in such environments.

Contribution

First Herschel far-infrared observations of low-metallicity dwarf galaxies, analyzing dust properties and evolution in these underexplored systems.

Findings

Dwarf galaxies have low dust masses and cooler dust temperatures.

Dust-to-gas ratios are lower than in more active galaxies but follow known metallicity relations.

High dust destruction rates suggest limited dust formation via stars or grain growth.

Abstract

We present here far-infrared photometry of galaxies in a sample that is relatively unexplored at these wavelengths: low-metallicity dwarf galaxies with moderate star formation rates. Four dwarf irregular galaxies from the $\mathrm{L{\small{ITTLE}}}$ $\mathrm{T{\small{HINGS}}}$ survey are considered, with deep $\textit{Herschel}$ PACS and SPIRE observations at 100 $\mu$m, 160 $\mu$m, 250 $\mu$m, 350 $\mu$m, and 500 $\mu$m. Results from modified-blackbody fits indicate that these galaxies have low dust masses and cooler dust temperatures than more actively star-forming dwarfs, occupying the lowest $L_\mathrm{TIR}$ and $M_\mathrm{dust}$ regimes seen among these samples. Dust-to-gas mass ratios of $\sim$10$^{-5}$ are lower, overall, than in more massive and active galaxies, but are roughly consistent with the broken power law relation between the dust-to-gas ratio and metallicity found for other low-metallicity systems. Chemical evolution modeling suggests that these dwarf galaxies are likely forming very little dust via stars or grain growth, and have very high dust destruction rates.