Gravity as main driver of non-thermal motions in massive star forming regions

¹ Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
² Instituto de Radio Astronomìa Milimètrica, Granada, Spain
³ School of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
⁴ School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA, UK
⁵ IAPS – INAF, via Fosso del Cavaliere, 100, 00133 Roma, Italy
⁶ Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland

Abstract

The origin of the observed non-thermal motions in massive star forming regions is still unclear. These motions can originate from local turbulence or from self-gravity and the two scenarios lead to two different star formation mechanisms. The recent findings of Heyer et al. ([5]) have supported self-gravity as main driver of the non-thermal motions, although without a clear interpretation of the results. In this contribution we introduce a new formalism to describe the relation between gravity and kinetic motion in massive star formation. We show that the Heyer findings are a particular result of this description and have a direct physical interpretation. We applied this formalism to different surveys of massive star forming regions covering all spatial scales from giant molecular clouds down to massive cores, including new data from massive candidate starless clumps. The results presented in this contribution strongly support a chaotic, gravitationally driven global collapse scenario as massive star formation mechanism.