Density distributions of outflow driven turbulence

TL;DR

This study uses 3D numerical simulations to analyze how outflows from star formation influence turbulence in molecular clouds, revealing unique density distribution characteristics and implications for star formation rates.

Contribution

It introduces a real-space outflow-driven turbulence model and compares its density PDFs and star formation rate predictions to traditional Fourier-space models.

Findings

Outflow-driven turbulence produces negatively skewed density PDFs.

The density PDF deviates from log-normal at low densities but fits well at high densities.

The core formation rate per free-fall time may be comparable between real-space and Fourier-space turbulence models.

Abstract

Protostellar jets and outflows are signatures of star formation and promising mechanisms for driving supersonic turbulence in molecular clouds. We quantify outflow-driven turbulence through three-dimensional numerical simulations using an isothermal version of the robust total variation diminishing code. We drive turbulence in real-space using a simplified spherical outflow model, analyse the data through density probability distribution functions (PDF), and investigate the Core Formation Rate per free-fall time (CFR_ff). The real-space turbulence driving method produces a negatively skewed density PDF possessing an enhanced tail on the low-density side. It deviates from the log-normal distributions typically obtained from Fourier-space turbulence driving at low densities, but can provide a good fit at high-densities, particularly in terms of mass weighted rather than volume weighted density PDF. Due to this fact, we suggest that the CFR_ff determined from a Fourier-driven turbulence model could be comparable to that of our particular real-space driving model, which has a ratio of solenoidal to compressional components from the resulting turbulence velocity fields of ~0.6.