GALACTIC STRUCTURE BASED ON THE ATLASGAL 870 mu m SURVEY

Abstract

The ATLASGAL 870 mu m continuum survey conducted with the APEX telescope is the first one covering the whole inner Galactic plane (60 degrees > l > -60 degrees and b < +/-1 degrees.5) in submillimeter (submm) continuum emission tracing the cold dust of dense and young star-forming regions. Here, we present the overall distribution of sources within our Galactic disk. The submm continuum emission is confined to a narrow range around the Galactic plane, but shifted on average by similar to 0.07 deg below the plane. Source number counts show strong enhancements toward the Galactic center, the spiral arms, and toward prominent star-forming regions. Comparing the distribution of ATLASGAL dust continuum emission to that of young intermediate-to high-mass young stellar objects (YSOs) derived from Spitzer data, we find similarities as well as differences. In particular, the distribution of submm dust continuum emission is significantly more confined to the plane than the YSO distribution (FWHM of 0.7 and 1.1 deg, corresponding to mean physical scale heights of approximately 46 and 80 pc, respectively). While this difference may partly be caused by the large extinction from the dense submm cores, gradual dispersal of stellar distributions after their birth could also contribute to this effect. Compared to other tracers of Galactic structure, the ATLASGAL data are strongly confined to a narrow latitude strip around the Galactic plane.