Massive Quiescent Cores in Orion. II. Core Mass Function

We have surveyed submillimeter continuum emission from relatively quiescentregions in the Orion molecular cloud to determine how the core mass function ina high mass star forming region compares to the stellar initial mass function.Such studies are important for understanding the evolution of cores to stars,and for comparison to formation processes in high and low mass star formingregions. We used the SHARC II camera on the Caltech Submillimeter Observatorytelescope to obtain 350 \micron data having angular resolution of about 9arcsec, which corresponds to 0.02 pc at the distance of Orion. Our analysiscombining dust continuum and spectral line data defines a sample of 51 Orionmolecular cores with masses ranging from 0.1 \Ms to 46 \Ms and a mean mass of9.8 \Ms, which is one order of magnitude higher than the value found in typicallow mass star forming regions, such as Taurus. The majority of these corescannot be supported by thermal pressure or turbulence, and are probablysupercritical.They are thus likely precursors of protostars. The core massfunction for the Orion quiescent cores can be fitted by a power law with anindex equal to -0.85$\pm$0.21. This is significantly flatter than the Salpeterinitial mass function and is also flatter than the core mass function found inlow and intermediate star forming regions. Thus, it is likely thatenvironmental processes play a role in shaping the stellar IMF later in theevolution of dense cores and the formation of stars in such regions.Comment: 30 pages, 10 figures, accepted by Ap