The JCMT and Herschel Gould Belt Surveys: a comparison of SCUBA-2 and Herschel data of dense cores in the Taurus dark cloud L1495
Hill, T.; Könyves, V.; Palmeirim, P.; White, G.; Di Francesco, J.; Griffin, M. J.; Marsh, K.; Pezzuto, S.; Ward-Thompson, D.; Johnstone, D.; André, P.; Fich, M.; Hatchell, J.; Pattle, K.; Kirk, H.; Buckle, J.; Broekhoven-Fiene, H.; Jenness, T.; Quinn, C.; Salji, C.; Tisi, S.; Walker-Smith, S.; Kirk, J. M.; Sadavoy, S.; Pineda, J.; Berry, D.; Beaulieu, S.; Mottram, J.; Nutter, D. J.; Currie, M.
United Kingdom, Canada, France, United States, Netherlands, Germany, Chile, Italy
Abstract
We present a comparison of Submillimetre Common User Bolometer Array-2 (SCUBA-2) 850-μm and Herschel 70-500-μm observations of the L1495 filament in the Taurus Molecular Cloud with the goal of characterizing the SCUBA-2 Gould Belt Survey (GBS) data set. We identify and characterize starless cores in three data sets: SCUBA-2 850-μm, Herschel 250-μm, and Herschel 250-μm spatially filtered to mimic the SCUBA-2 data. SCUBA-2 detects only the highest-surface-brightness sources, principally detecting protostellar sources and starless cores embedded in filaments, while Herschel is sensitive to most of the cloud structure, including extended low-surface-brightness emission. Herschel detects considerably more sources than SCUBA-2 even after spatial filtering. We investigate which properties of a starless core detected by Herschel determine its detectability by SCUBA-2, and find that they are the core's temperature and column density (for given dust properties). For similar-temperature cores, such as those seen in L1495, the surface brightnesses of the cores are determined by their column densities, with the highest-column-density cores being detected by SCUBA-2. For roughly spherical geometries, column density corresponds to volume density, and so SCUBA-2 selects the densest cores from a population at a given temperature. This selection effect, which we quantify as a function of distance, makes SCUBA-2 ideal for identifying those cores in Herschel catalogues that are closest to forming stars. Our results can now be used by anyone wishing to use the SCUBA-2 GBS data set.