Evolution of Class0 protostars: Models vs. Observations

Abstract

The rates at which mass accumulates into protostellar cores can now be predicted in numerical simulations. Our purpose here is to develop methods to compare the statistical properties of the predicted protostars with the observable parameters. This requires (1) an evolutionary scheme to convert numerically-derived mass accretion rates into evolutionary tracks and (2) a technique to compare the tracks to the observed statistics of protostars. Here, we use a 3D-Kolmogorov-Smirnov test to quantitatively compare model evolutionary tracks and observations of Class0 protostars. We find that the wide range of accretion functions and timescales associated with gravoturbulent simulations naturally overcome difficulties associated with schemes that use a fixed accretion pattern. This implies that the location of a protostar on an evolutionary track does not precisely determine the present age or final accrued mass. Rather, we find that predictions of the final mass for protostars from observed Tbol-Lbol values are uncertain by a factor of two and that the bolometric temperature is not always a reliable measure of the evolutionary stage. Furthermore, we constrain several parameters of the evolutionary scheme and estimate a lifetime of Class0 sources of 2-6*10^4yrs, which is related to the local free-fall time and thus to the local density at the onset of the collapse. Models with Mach numbers smaller than six are found to best explain the observational data. Generally, only a probability of 70% was found that our models explain the current observations. This is caused by not well understood selection effects in the observational sample and the simplified assumptions in the models.