2012ApJ...756..119W

In this paper, we investigate the extent to which observations of molecular clouds can correctly identify and measure star-forming clumps. We produced a synthetic column density map and a synthetic spectral-line data cube from the simulated collapse of a 5000 M_☉ molecular cloud. By correlating the clumps found in the simulation to those found in the synthetic observations, clump masses derived from spectral-line data cubes were found to be quite close to the true physical properties of the clumps. We also find that the "observed" clump mass function (CMF) derived from the column density map is shifted by a factor of ∼3 higher than the true CMF, due to projection of low-density material along the line of sight. Alves et al. first proposed that a shift of a CMF to higher masses by a factor of three can be attributed to a star formation efficiency of 30%. Our results indicate that this finding may instead be due to an overestimate of clump masses determined from column density observations.