Universität zu Köln

Csengeri, T., Weiss, A., Wyrowski, F., Menten, K. M., Urquhart, J. S., Leurini, S., Schuller, F., Beuther, H., Bontemps, S., Bronfman, L., Henning, Th and Schneider, N. (2016). The ATLASGAL survey: distribution of cold dust in the Galactic plane Combination with Planck data. Astron. Astrophys., 585. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

Context. Sensitive ground-based submillimeter surveys, such as ATLASGAL, provide a global view on the distribution of cold dense gas in the Galactic plane at up to two-times better angular-resolution compared to recent space-based surveys with Herschel. However, a drawback of ground-based continuum observations is that they intrinsically filter emission, at angular scales larger than a fraction of the field-of-view of the array, when subtracting the sky noise in the data processing. The lost information on the distribution of diffuse emission can be, however, recovered from space-based, all-sky surveys with Planck. Aims. Here we aim to demonstrate how this information can be used to complement ground-based bolometer data and present reprocessed maps of the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) survey. Methods. We use the maps at 353 GHz from the Planck/HFI instrument, which performed a high sensitivity all-sky survey at a frequency close to that of the APEX/LABOCA array, which is centred on 345 GHz. Complementing the ground-based observations with information on larger angular scales, the resulting maps reveal the distribution of cold dust in the inner Galaxy with a larger spatial dynamic range. We visually describe the observed features and assess the global properties of dust distribution. Results. Adding information from large angular scales helps to better identify the global properties of the cold Galactic interstellar medium. To illustrate this, we provide mass estimates from the dust towards the W43 star-forming region and estimate a column density contrast of at least a factor of five between a low intensity halo and the star-forming ridge. We also show examples of elongated structures extending over angular scales of 0.5 degrees, which we refer to as thin giant filaments. Corresponding to >30 pc structures in projection at a distance of 3 kpc, these dust lanes are very extended and show large aspect ratios. We assess the fraction of dense gas by determining the contribution of the APEX/LABOCA maps to the combined maps, and estimate 2-5% for the dense gas fraction (corresponding to A(v) > 7 mag) on average in the Galactic plane. We also show probability distribution functions of the column density (N-PDF), which reveal the typically observed log-normal distribution for low column density and exhibit an excess at high column densities. As a reference for extragalactic studies, we show the line-of-sight integrated N-PDF of the inner Galaxy, and derive a contribution of this excess to the total column density of similar to 2.2%, corresponding to N-H2 = 2.92 x 10(22) cm(-2). Taking the total flux density observed in the maps, we provide an independent estimate of the mass of molecular gas in the inner Galaxy of similar to 1 x 10(9) M-circle dot, which is consistent with previous estimates using CO emission. From the mass and dense gas fraction (f(DG)), we estimate a Galactic SFR of (M) over dot = 1.3 M-circle dot yr(-1). Conclusions. Retrieving the extended emission helps to better identify massive giant filaments which are elongated and confined structures. We show that the log-normal distribution of low column density gas is ubiquitous in the inner Galaxy. While the distribution of diffuse gas is relatively homogenous in the inner Galaxy, the central molecular zone (CMZ) stands out with a higher dense gas fraction despite its low star formation efficiency. Altogether our findings explain well the observed low star formation efficiency of the Milky Way by the low fDG in the Galactic ISM. In contrast, the high fDG observed towards the CMZ, despite its low star formation activity, suggests that, in that particular region of our Galaxy, high density gas is not the bottleneck for star formation.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Csengeri, T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Weiss, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wyrowski, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Menten, K. M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Urquhart, J. S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Leurini, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schuller, F. UNSPECIFIED UNSPECIFIED UNSPECIFIED Beuther, H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bontemps, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bronfman, L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Henning, Th UNSPECIFIED UNSPECIFIED UNSPECIFIED Schneider, N. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-291167
DOI:	10.1051/0004-6361/201526639
Journal or Publication Title:	Astron. Astrophys.
Volume:	585
Date:	2016
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language DENSITY PROBABILITY-DISTRIBUTION; INFRARED-DARK CLOUD; STAR-FORMATION RATE; MOLECULAR CLOUDS; MILKY-WAY; COLUMN DENSITY; GRAVITATIONAL COLLAPSE; FORMATION EFFICIENCY; INITIAL HIGHLIGHTS; CLUSTER-FORMATION Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/29116