2017MNRAS.465.1316M

Motivated by the non-linear star formation efficiency found in recent numerical simulations by a number of workers, we perform high-resolution adaptive mesh refinement simulations of star formation in self-gravitating turbulently driven gas. As we follow the collapse of this gas, we find that the character of the flow changes at two radii, the disc radius r_d and the radius r_*, where the enclosed gas mass exceeds the stellar mass. Accretion starts at large scales and works inwards. In line with recent analytical work, we find that the density evolves to a fixed attractor, ρ(r, t) - ρ(r), for r_d < r < r_*; mass flows through this structure on to a sporadically gravitationally unstable disc and from thence on to the star. In the bulk of the simulation box, we find that the random motions v_T ∼ r^p with p ∼ 0.5 are in agreement with Larson's size-linewidth relation. In the vicinity of massive star-forming regions, we find p ∼ 0.2-0.3, as seen in observations. For r < r_*, v_T increases inwards, with p = -1/2. Finally, we find that the total stellar mass M_*(t) ∼ t² is in line with previous numerical and analytic work that suggests a non-linear rate of star formation.