JINGLE, a JCMT legacy survey of dust and gas for galaxy evolution studies: II. SCUBA-2 850 μm data reduction and dust flux density catalogues

Abstract

We present the SCUBA-2 850 $\hat{I}¼m$ component of JINGLE, the new JCMT large survey for dust and gas in nearby galaxies, which with 193 galaxies is the largest targeted survey of nearby galaxies at 850 $\hat{I}¼m$. We provide details of our SCUBA-2 data reduction pipeline, optimised for slightly extended sources, and including a calibration model adjusted to match conventions used in other far-infrared data. We measure total integrated fluxes for the entire JINGLE sample in 10 infrared/submillimetre bands, including all WISE, Herschel-PACS, Herschel-SPIRE and SCUBA-2 850 $\hat{I}¼m$ maps, statistically accounting for the contamination by CO(J=3-2) in the 850 $\hat{I}¼m$ band. Of our initial sample of 193 galaxies, 191 are detected at 250 $\hat{I}¼m$ with a $\ge$ 5$\ddot{I}ƒ$ significance. In the SCUBA-2 850 $\hat{I}¼m$ band we detect 126 galaxies with $\ge$ 3$\ddot{I}ƒ$ significance. The distribution of the JINGLE galaxies in far-infrared/sub-millimetre colour-colour plots reveals that the sample is not well fit by single modified-blackbody models that assume a single dust-emissivity index $({\hat{I}}^2)$. Instead, our new 850 $\hat{I}¼m$ data suggest either that a large fraction of our objects require ${\hat{I}}^2<1.5$, or that a model allowing for an excess of sub-mm emission (e.g., a broken dust emissivity law, or a very cold dust component 10 K) is required. We provide relations to convert far-infrared colours to dust temperature and ${\hat{I}}^2$ for JINGLE-like galaxies. For JINGLE the FIR colours correlate more strongly with star-formation rate surface-density rather than the stellar surface-density, suggesting heating of dust is greater due to younger rather than older stellar-populations, consistent with the low proportion of early-type galaxies in the sample.

Accepted by MNRAS; data available at http://www.star.ucl.ac.uk/JINGLE/