SHARC 350 Micron Mapping of the Galactic Center from the Caltech Submillimeter Observatory

Abstract

Using the 20-pixel camera SHARC, we have surveyed the 350 micron emission from a 60 arcminute by 12 arcminute region in the Galactic center. A comparable region has been observed at 800 microns by Lis & Carlstrom (1994); the SHARC map has better spatial resolution and sensitivity to extended emission, however. This paper introduces several features not visible in prior maps of dust emission. We have detected a 10+ pc band of emission peaking at l = -0.14 degrees, b = +0.02 degrees, which is probably associated with the 'negative velocity arc' observed in 13CO (Bally et al. 1988). We suggest an association of a rounded 350 micron feature near the Radio Arc with an expanding shell observed in CS (Tsuboi, Ukita, & Handa 1997). Faint emission at the same Galactic longitude as the Dust Ridge (Lis & Carlstrom 1994) but at opposite latitude is visible as well as a compact source at the base of a thermal radio filament at negative Galactic latitude. Diffuse dust emission within a few arcminutes of the Sgr D core is detected for the first time. 350 micron sources are associated with both H2O masers in Sgr D, but only one out of four OH masers (Mehringer et al. 1998). The mean 350 micron / 800 micron flux ratio for the Galactic center is approximately 17 (beta = 2.0) over the map but is higher (beta = 2.5) in parts of the Dust Ridge and lower in Sgr B2 (N).