Implementing and comparing sink particles in AMR and SPH
  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.
