The SCUBA HAlf Degree Extragalactic Survey (SHADES) -- VI. 350 micron mapping of submillimetre galaxies

TL;DR

This study uses 350 micron observations to analyze the properties of submillimetre galaxies, revealing their dust content, luminosities, temperatures, and star-formation rates, and providing new constraints on their source counts.

Contribution

First 350 micron follow-up survey of SHADES SMGs providing detailed dust and star-formation properties and source count constraints.

Findings

SMGs are dust-rich, luminous, star-forming galaxies.

Typical dust temperature around 35 K with a broad distribution.

Estimated 350 micron source counts are 200-500 deg^-2.

Abstract

A follow-up survey using the Submillimetre High-Angular Resolution Camera (SHARC-II) at 350 microns has been carried out to map the regions around several 850 micron-selected sources from the Submillimetre HAlf Degree Extragalactic Survey (SHADES). These observations probe the infrared luminosities and hence star-formation rates in the largest existing, most robust sample of submillimetre galaxies (SMGs). We measure 350 micron flux densities for 24 850 micron sources, seven of which are detected at >2.5-sigma within a 10 arcsec search radius of the 850 micron positions. When results from the literature are included the total number of 350 micron flux density constraints of SHADES SMGs is 31, with 15 detections. We fit a modified blackbody to the far-infrared (FIR) photometry of each SMG, and confirm that typical SMGs are dust-rich (Mdust~9x10^8 Msun), luminous (Lfir~2x10^12 Lsun), star-forming galaxies with intrinsic dust temperatures of ~35 K and star-formation rates of ~400 Msun/yr. We have measured the temperature distribution of SMGs and find that the underlying distribution is slightly broader than implied by the error bars, and that most SMGs are at 28 K with a few hotter. We also place new constraints on the 350 micron source counts, N350(>25mJy)~200-500 deg^-2.