The ATLASGAL survey: a catalog of dust condensations in the Galactic plane

Abstract

Context. The formation processes and the evolutionary stages of high-mass stars are poorly understood compared to low-mass stars. Large-scale surveys are needed to provide an unbiased census of high column density sites that can potentially host precursors to high-mass stars. Aims. The ATLASGAL survey covers 420 sq. degree of the Galactic plane, between −80 • < < +60 • at 870 μm. Here we identify the population of embedded sources throughout the inner Galaxy. With this catalog we first investigate the general statistical properties of dust condensations in terms of their observed parameters, such as flux density and angular size. Then using mid-infrared surveys we aim to investigate their star formation activity and the Galactic distribution of star-forming and quiescent clumps. Our ultimate goal is to determine the statistical properties of quiescent and star-forming clumps within the Galaxy and to constrain the star formation processes. Methods. We optimized the source extraction method, referred to as MRE-GCL, for the ATLASGAL maps in order to generate a catalog of compact sources. This technique is based on multiscale filtering to remove extended emission from clouds to better determine the parameters corresponding to the embedded compact sources. In a second step we extracted the sources by fitting 2D Gaussians with the Gaussclumps algorithm. Results. We have identified in total 10861 compact submillimeter sources with fluxes above 5σ. Completeness tests show that this catalog is 97% complete above 5σ and >99% complete above 7σ. Correlating this sample of clumps with mid-infrared point source catalogs (MSX at 21.3 μm and WISE at 22 μm), we have determined a lower limit of 33% that is associated with embedded protostellar objects. We note that the proportion of clumps associated with mid-infrared sources increases with increasing flux density, achieving a rather constant fraction of ∼75% of all clumps with fluxes over 5 Jy/beam being associated with star formation. Examining the source counts as a function of Galactic longitude, we are able to identify the most prominent star-forming regions in the Galaxy. Conclusions. We present here the compact source catalog of the full ATLASGAL survey and investigate their characteristic properties. From the fraction of the likely massive quiescent clumps (∼25%), we estimate a formation time scale of ∼7.5 ± 2.5 × 10 4 yr for the deeply embedded phase before the emergence of luminous young stellar objects. Such a short duration for the formation of high-mass stars in massive clumps clearly proves that the earliest phases have to be dynamic with supersonic motions.

The First Detections of the Key Prebiotic Molecule Po in Star-Forming Regions

“…We have used Equations (15) and (17) to derive the dust opacity and the hydrogen column density of W51 and W3(OH) from the dust continuum emission from ATLASGAL (870 μm; Csengeri et al 2014) and SCUBA (850 μm; Di Francesco et al 2008) surveys, respectively. We have considered that the dust temperature is the same as the excitation temperature derived for PN, 35 K. We have adopted a gas-to-dust ratio of 100 and κ ν = 1.85 cm 2 g −1 , from interpolation of column 5 of Table 1 of Ossenkopf & Henning (1994).…”

ALMA survey of massive cluster progenitors from ATLASGAL

“…Butler & Tan 2012;Tackenberg et al 2012;Traficante et al 2015;Svoboda et al 2016;Csengeri et al 2017), which show that the early evolutionary stages are short lived (e.g. Motte et al 2007;Csengeri et al 2014), as star formation proceeds rapidly. Using the Atacama Large Millimeter/submillimeter Array (ALMA), here we present the first results of a statistical study of early stage fragmentation to shed light on the physical processes at the origin of high-mass collapsing entities and to search for the youngest precursors of O-type stars.…”

A search for water masers associated with class II methanol masers – II. Longitude range 341° to 6°

“…About 95 per cent of the MMB masers lie within the region surveyed by ATLASGAL. Urquhart et al (2013) used the ATLASGAL source catalogues of Contreras et al (2013) and Csengeri et al (2014) to match the methanol masers with an associated dust clump. They used a criteria of being within 120 arcseconds of a peak in the 870 µm emission to define an association as this was the largest clump radius .…”

“…Recently, there have been two large, unbiased surveys of the Galactic Plane in the submillimetre regime. The Bolocam Galactic Plane Survey (BGPS; Rosolowsky et al 2010) at 1.1 mm and the APEX Telescope Large Area Survey of the GALaxy (ATLASGAL; Schuller et al 2009;Contreras et al 2013;Csengeri et al 2014) at 870 µm.…”