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http://hdl.handle.net/20.500.12386/23753
Titolo: | Detection of two power-law tails in the probability distribution functions of massive GMCs | Autori: | Schneider, N. Bontemps, S. Girichidis, P. Rayner, T. Motte, F. André, P. Russeil, D. Abergel, A. Anderson, L. Arzoumanian, D. BENEDETTINI, Milena Csengeri, T. Didelon, P. di, Francesco J. Griffin, M. Hill, T. Klessen, R. S. Ossenkopf, V. PEZZUTO, Stefano Rivera-Ingraham, A. SPINOGLIO, Luigi Giuseppe Maria Tremblin, P. Zavagno, A. |
Data pubblicazione: | 2015 | Rivista: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | Numero: | 453 | Da pagina:: | L41 | Abstract: | We report the novel detection of complex high column density tails in the probability distribution functions (PDFs) for three high-mass star-forming regions (CepOB3, MonR2, NGC 6334), obtained from dust emission observed with Herschel. The low column density range can be fitted with a lognormal distribution. A first power-law tail starts above an extinction (AV) of ̃6-14. It has a slope of α 1.3-2 for the &ρ ≈ r-α profile for an equivalent density distribution (spherical or cylindrical geometry), and is thus consistent with free-fall gravitational collapse. Above AV ̃40, 60, and 140, we detect an excess that can be fitted by a flatter power-law tail with α > 2. It correlates with the central regions of the cloud (ridges/hubs) of size ̃;1 pc and densities above 104 cm-3. This excess may be caused by physical processes that slow down collapse and reduce the flow of mass towards higher densities. Possible are: (1) rotation, which introduces an angular momentum barrier, (2) increasing optical depth and weaker cooling, (3) magnetic fields, (4) geometrical effects, and (5) protostellar feedback. The excess/second power-law tail is closely linked to high-mass star-formation though it does not imply a universal column density threshold for the formation of (high-mass) stars. | URI: | http://hdl.handle.net/20.500.12386/23753 | URL: | https://academic.oup.com/mnrasl/article/453/1/L41/983239 | ISSN: | 0035-8711 | DOI: | 10.1093/mnrasl/slv101 | Bibcode ADS: | 2015MNRAS.453L..41S | Fulltext: | open |
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