Submillimetre surveys
Mark Thompson is the Principal Investigator of the SCUBA-2 "All-Sky" Survey (SASSy).
SASSy is an 850 micron SCUBA-2 survey of the Outer Galaxy, stretching from a Galactic longitude of 60 to 240 degrees and covering the inner and outer Perseus Arms of the Milky Way. In the inner part of the Perseus Arm (SASSy Perseus) we will cover a latitude range of +/- 1 degree, extending to cover the prominent Cygnus-X star forming region. In the outer parts of the Galaxy (OGS) we will expand this range to +/-2 degrees in order to cover the larger number of objects found at greater latitudes in this region. The target 1-sigma depth of the survey is 30 mJy/beam, which is ideally matched to that of the APEX ATLASGAL survey and the Herschel Hi-GAL survey.
The goals of SASSy are to identify the coldest and earliest regions of star formation along the Galactic Plane by combining 850 micron data with shorter wavelengths from the Herschel Hi-GAL survey. Herschel's performance at longer wavelengths is degraded by a loss in angular resolution and sensitivity, and so combining SASSy with Hi-GAL enables us to pick up cold molecular cores peaking longwards of 350 microns. Survey operations are currently underway at the JCMT, but as a preview of what we hope to accomplish, here is the SASSy Science Verification image obtained of the NGC7538 region. The contours are from the SCUBA Legacy Survey and illustrate the exquisite dynamic range of SCUBA-2, even in poor weather. The extended filamentary structure of the cloud is clearly visible, and the compact cores in the SCUBA image are revealed to lie in low surface brightness envelopes of low column density gas.
Mark Thompson is Survey Manager of the JCMT Plane Survey (JPS).
The JCMT Plane Survey is a survey of targeted regions of the Galactic Plane at 450 and 850 microns, with the aim of going almost a factor of 10 deeper than any sub-mm Galactic Plane survey has done before. JPS will reveal the population of star forming clumps out to the edge of the Milky Way Galaxy and trace the delicate filamentary structure of molecular clouds, enabling us to derive the physical properties of the filaments discovered by the Herschel Hi-GAL survey. Survey operations for JPS have commenced on the JCMT. The image below shows a section of the Galactic Plane observed with SCUBA-2 at 850 microns during commissioning (image credit: Joint Astronomy Centre) and reveals the complex structure that we aim to understand.
