Galactic cold cores

VIII. Filament formation and evolution: Filament properties in context with evolutionary models ^⋆

¹ European Space Astronomy Centre (ESA/ESAC), Operations Department, Villanueva de la Cañada (Madrid), Spain
e-mail: alana.rivera@sciops.esa.int
² Université de Toulouse, UPS-OMP, IRAP, Toulouse, France
³ CNRS, IRAP, 9 Av. colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
⁴ Department of Physics, PO Box 64, 00014 University of Helsinki, Finland
⁵ Institut UTINAM, CNRS 6213, OSU THETA, Université de Franche-Comté, 41bis avenue de l’Observatoire, 25000 Besançon, France
⁶ Laboratoire AIM, CEA/DSM/Irfu – CNRS/INSU – Université Paris Diderot, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
⁷ Finnish Centre for Astronomy with ESO, University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland
⁸ Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8, Canada
⁹ LERMA, Observatoire de Paris, PSL Research University, CNRS, UMR 8112, 75014 Paris, France
¹⁰ Sorbonne Universités, UPMC Univ. Paris 6, UMR 8112, LERMA, 75005 Paris, France
¹¹ Infrared Processing Analysis Center, California Institute of Technology, 770 S. Wilson Ave., Pasadena, CA 91125, USA
¹² IAS, CNRS (UMR8617), Université Paris Sud, Bât. 121, 91400 Orsay, France
¹³ Jeremiah Horrocks Institute, University of Central Lancashire, Preston, Lancashire, PR1 2HE, UK
¹⁴ Eötvös University, Department of Astronomy, Pázmány P. s. 1/a, 1117 Budapest, Hungary

Received: 18 March 2016
Accepted: 23 February 2017

Abstract

Context. The onset of star formation is intimately linked with the presence of massive unstable filamentary structures. These filaments are therefore key for theoretical models that aim to reproduce the observed characteristics of the star formation process in the Galaxy.

Aims. As part of the filament study carried out by the Herschel Galactic Cold Cores Key Programme, here we study and discuss the filament properties presented in GCC VII (Paper I) in context with theoretical models of filament formation and evolution.

Methods. A conservatively selected sample of filaments located at a distance D< 500 pc was extracted from the GCC fields with the getfilaments algorithm. The physical structure of the filaments was quantified according to two main components: the central (Gaussian) region of the filament (core component), and the power-law-like region dominating the filament column density profile at larger radii (wing component). The properties and behaviour of these components relative to the total linear mass density of the filament and the column density of its environment were compared with the predictions from theoretical models describing the evolution of filaments under gravity-dominated conditions.

Results. The feasibility of a transition from a subcritical to supercritical state by accretion at any given time is dependent on the combined effect of filament intrinsic properties and environmental conditions. Reasonably self-gravitating (high M_line,core) filaments in dense environments (A_V≳ 3 mag) can become supercritical on timescales of t ~ 1 Myr by accreting mass at constant or decreasing width. The trend of increasing M_line,tot (M_line,core and M_line,wing) and ridge A_V with background for the filament population also indicates that the precursors of star-forming filaments evolve coevally with their environment. The simultaneous increase of environment and filament A_V explains the observed association between dense environments and high M_line,core values, and it argues against filaments remaining in constant single-pressure equilibrium states. The simultaneous growth of filament and background in locations with efficient mass assembly, predicted in numerical models of filaments in collapsing clouds, presents a suitable scenario for the fulfillment of the combined filament mass−environment criterium that is in quantitative agreement with Herschel observations.