Star formation efficiency in turbulent clouds

TL;DR

This paper introduces a simple model for star formation efficiency in turbulent molecular clouds, based on a log-normal density distribution, core mass function, and Jeans mass, revealing a power-law relation and maximum efficiency.

Contribution

The model links star formation efficiency to cloud properties using a log-normal density distribution and a Salpeter-like core mass function, providing a new analytical approach.

Findings

SFE follows a power-law with cloud to Jeans mass ratio.

Maximum SFE is approximately one-third.

Result is independent of turbulent Mach number.

Abstract

Here we present a simple, but nevertheless, instructive model for the star formation efficiency in turbulent molecular clouds. The model is based on the assumption of log-normal density distribution which reflects the turbulent nature of the interstellar medium (ISM). Together with the number count of cloud cores, which follows a Salpeter-like core mass function (CMF), and the minimum mass for the collapse of individual cloud cores, given by the local Jeans mass, we are able to derive the SFE for clouds as a function of their Jeans masses. We find a very generic power-law, SFE \propto (M_cloud/M_J)^{-0.26} and a maximum SFE_max \sim 1/3 for the Salpeter case. This result is independent of the turbulent Mach number but fairly sensitive to variations of the CMF.