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Cloud Structure of Three Galactic Infrared Dark Star-forming Regions from Combining Ground- and Space-based Bolometric Observations

Lin, Yuxin and Liu, Hauyu Baobab and Dale, James E. and Li, Di and Busquet, Gemma and Zhang, Zhi-Yu and Ginsburg, Adam and Galván-Madrid, Roberto and Kovács, Attila and Koch, Eric and Qian, Lei and Wang, Ke and Longmore, Steve and Chen, Huei-Ru and Walker, Daniel (2017) Cloud Structure of Three Galactic Infrared Dark Star-forming Regions from Combining Ground- and Space-based Bolometric Observations. Astrophysical Journal, 840 (1). Art. No. 22. ISSN 1538-4357.

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We have modified the iterative procedure introduced by Lin et al., to systematically combine the submillimeter images taken from ground-based (e.g., CSO, JCMT, APEX) and space (e.g., Herschel, Planck) telescopes. We applied the updated procedure to observations of three well-studied Infrared Dark Clouds (IRDCs): G11.11−0.12, G14.225−0.506, and G28.34+0.06, and then performed single-component, modified blackbody fits to each pixel to derive ~10'' resolution dust temperature and column density maps. The derived column density maps show that these three IRDCs exhibit complex filamentary structures embedded with rich clumps/cores. We compared the column density probability distribution functions (N-PDFs) and two-point correlation (2PT) functions of the column density field between these IRDCs with several OB-cluster-forming regions. Based on the observed correlation between the luminosity-to-mass ratio and the power-law index of the N-PDF, and complementary hydrodynamical simulations for a 10^4 M_⊙ molecular cloud, we hypothesize that cloud evolution can be better characterized by the evolution of the (column) density distribution function and the relative power of dense structures as a function of spatial scales, rather than merely based on the presence of star-forming activity. An important component of our approach is to provide a model-independent quantification of cloud evolution. Based on the small analyzed sample, we propose four evolutionary stages, namely, cloud integration, stellar assembly, cloud pre-dispersal, and dispersed cloud. The initial cloud integration stage and the final dispersed cloud stage may be distinguished from the two intermediate stages by a steeper than −4 power-law index of the N-PDF. The cloud integration stage and the subsequent stellar assembly stage are further distinguished from each other by the larger luminosity-to-mass ratio (>40 L_⊙/M_⊙) of the latter. A future large survey of molecular clouds with high angular resolution may establish more precise evolutionary tracks in the parameter space of N-PDF, 2PT function, and luminosity-to-mass ratio.

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Additional Information:© 2017 The American Astronomical Society. Received 2016 October 29; revised 2017 April 6; accepted 2017 April 7; published 2017 May 2. We are grateful to our referee for helpful comments that led to improvement of the paper. This work is partially supported by the International Partnership Program of Chinese Academy of Sciences, grant No. 114A11KYSB20160008 and National Natural Science Foundation of China No. 11373038. Y.X.L. acknowledge Bo Zhang and Guangxing Li for useful suggestions and discussions. G.B. acknowledges the support of the Spanish Ministerio de Enconomia y Competitividad (MINECO) under grant FPDI-2013-18204. G.B. is supported by the Spanish MINECO grant AYA2014-57369-C3-1-P. Z.Y.Z. acknowledges support from the European Research Council in the form of the Advanced Investigator Programme, 321302, cosmicism. R.G.-M. acknowledges support from UNAM-PAPIIT program IA102817. K.W. acknowledges support from Deutsche Forschungsgemeinschaft (DFG) grant WA3628-1/1 through priority program 1573 (Physics of the Interstellar Medium). The JCMT is operated by the East Asian Observatory on behalf of The National Astronomical Observatory of Japan, Academia Sinica Institute of Astronomy and Astrophysics, the Korea Astronomy and Space Science Institute, the National Astronomical Observatories of China and the Chinese Academy of Sciences (grant No. XDB09000000), with additional funding support from the Science and Technology Facilities Council of the United Kingdom and participating universities in the United Kingdom and Canada. The JCMT has historically been operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the United Kingdom, the National Research Council of Canada and the Netherlands Organization for Scientific Research. Additional funds for the construction of Q2 SCUBA-2 were provided by the Canada Foundation for Innovation.
Funding AgencyGrant Number
Chinese Academy of Sciences114A11KYSB20160008
National Natural Science Foundation of China11373038
Ministerio de Economía y Competitividad (MINECO)FPDI-2013-18204
Ministerio de Economía y Competitividad (MINECO)AYA2014-57369-C3-1-P
European Research Council (ERC)321302
Universidad Nacional Autónoma de MéxicoIA102817
Deutsche Forschungsgemeinschaft (DFG) WA3628-1/1
Chinese Academy of SciencesXDB09000000
Science and Technology Facilities Council (STFC)UNSPECIFIED
Canada Foundation for InnovationUNSPECIFIED
Subject Keywords:ISM: structure – stars: formation – submillimeter: ISM
Record Number:CaltechAUTHORS:20170502-133729026
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Official Citation:Yuxin Lin et al 2017 ApJ 840 22
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77129
Deposited By: Tony Diaz
Deposited On:02 May 2017 21:42
Last Modified:14 Jul 2017 21:39

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