Stellar and substellar initial mass function: a model that implements gravoturbulent fragmentation and accretion

TL;DR

This paper presents a model for the stellar initial mass function based on gravoturbulent fragmentation and competitive accretion in molecular clouds, successfully reproducing observed IMFs with specific parameters.

Contribution

The model integrates gravoturbulent fragmentation and accretion processes to derive the IMF, offering a physically motivated explanation for its shape and parameters.

Findings

IMF best matches observations with x=0.25

Star formation timescale around 5 Myr

Star formation efficiency approximately 10%

Abstract

In this work, we derive the stellar initial mass function (IMF) from the superposition of mass distributions of dense cores, generated through gravoturbulent fragmentation of unstable clumps in molecular clouds (MCs) and growing through competitive accretion. MCs are formed by the turbulent cascade in the interstellar medium at scales L from 100 down to ~0.1 pc. Their internal turbulence is essentially supersonic and creates clumps with a lognormal distribution of densities n. Our model is based on the assumption of a power-law relationship between clump mass and clump density: n~m^x, where x is a scale-free parameter. Gravitationally unstable clumps are assumed to undergo isothermal fragmentation and produce protostellar cores with a lognormal mass distribution, centred around the clump Jeans mass. Masses of individual cores are then assumed to grow further through competitive accretion until the rest of the gas within the clump is being exhausted. The observed IMF is best reproduced for a choice of x=0.25, for a characteristic star formation timescale of ~5 Myr, and for a low star formation efficiency of ~10 %.