Implementing and comparing sink particles in AMR and SPH

TL;DR

This paper develops and compares sink particle implementations in AMR and SPH simulations to improve modeling of star formation, emphasizing the importance of physical collapse criteria beyond density thresholds.

Contribution

It introduces a new sink particle module in the AMR code FLASH and compares its performance with SPH simulations, highlighting the necessity of additional collapse indicators.

Findings

Encouraging agreement between AMR and SPH sink particle properties.

Density threshold alone is insufficient for sink creation in supersonic flows.

Additional physical collapse criteria are necessary for accurate modeling.

Abstract

We implemented sink particles in the Adaptive Mesh Refinement (AMR) code FLASH to model the gravitational collapse and accretion in turbulent molecular clouds and cores. Sink particles are frequently used to measure properties of star formation in numerical simulations, such as the star formation rate and efficiency, and the mass distribution of stars. We show that only using a density threshold for sink particle creation is insufficient in case of supersonic flows, because the density can exceed the threshold in strong shocks that do not necessarily lead to local collapse. Additional physical collapse indicators have to be considered. We apply our AMR sink particle module to the formation of a star cluster, and compare it to a Smoothed Particle Hydrodynamics (SPH) code with sink particles. Our comparison shows encouraging agreement of gas and sink particle properties between the AMR and SPH code.