Herschel photometric observations of the low metallicity dwarf galaxy NGC 1705

TL;DR

This study uses Herschel observations to analyze the low metallicity dwarf galaxy NGC 1705, revealing a significant cold dust component and circumnuclear IR-bright regions, with implications for understanding dust properties in such galaxies.

Contribution

First detailed Herschel photometry of NGC 1705 highlighting a cold dust component and circumnuclear IR regions in a low metallicity dwarf galaxy.

Findings

Detection of two IR-bright circumnuclear regions.

Identification of a sub-mm excess indicating cold dust.

Modeling suggests an additional cold dust component.

Abstract

We present Herschel SPIRE and PACS photometeric observations of the low metallicity (Z ~ 0.35 solar) nearby dwarf galaxy, NGC 1705, in six wavelength bands as part of the Dwarf Galaxy Survey guaranteed time Herschel Key Program. We confirm the presence of two dominant circumnuclear IR-bright regions surrounding the central super star cluster that had been previously noted at mid-IR wavelengths and in the sub-mm by LABOCA. On constructing a global spectral energy distribution using the SPIRE and PACS photometry, in conjunction with archival IR measurements, we note the presence of an excess at sub-mm wavelengths. This excess suggests the presence of a significant cold dust component within NGC 1705 and was modeled as an additional cold component in the SED. Although alternative explanations for the sub-mm excess beyond 350 microns, such as changes to the dust emissivity cannot be ruled out, the most likely explanation for the observed submillimetre excess is that of an additional cold dust component.