Schneider, N.N.SchneiderBontemps, S.S.BontempsGirichidis, P.P.GirichidisRayner, T.T.RaynerMotte, F.F.MotteAndré, P.P.AndréRusseil, D.D.RusseilAbergel, A.A.AbergelAnderson, L.L.AndersonArzoumanian, D.D.ArzoumanianBENEDETTINI, MilenaMilenaBENEDETTINICsengeri, T.T.CsengeriDidelon, P.P.Didelondi, Francesco J.Francesco J.diGriffin, M.M.GriffinHill, T.T.HillKlessen, R. S.R. S.KlessenOssenkopf, V.V.OssenkopfPEZZUTO, StefanoStefanoPEZZUTORivera-Ingraham, A.A.Rivera-IngrahamSPINOGLIO, Luigi Giuseppe MariaLuigi Giuseppe MariaSPINOGLIOTremblin, P.P.TremblinZavagno, A.A.Zavagno2020-03-312020-03-3120150035-8711http://hdl.handle.net/20.500.12386/23753We 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.STAMPAenArticle10.1093/mnrasl/slv1012-s2.0-84941285925000361300300009https://academic.oup.com/mnrasl/article/453/1/L41/9832392015MNRAS.453L..41SFIS/05 - ASTRONOMIA E ASTROFISICA