Large-area mapping at 850 μm.: V.: Analysis of the clump distribution in the Orion A south molecular cloud

We present results from a 2300 arcmin(2) survey of the Orion A molecular cloud at 450 and 850 mu m using the Submillimeter Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope. The region mapped lies directly south of the OMC 1 cloud core and includes OMC 4, OMC 5, HH 1/2, HH 34, and L1641N. We identify 71 independent clumps in the 850 mu m map and compute size, flux, and degree of central concentration in each. Comparison with isothermal, pressure-confined, self-gravitating Bonnor-Ebert spheres implies that the clumps have internal temperatures T-d similar to 22 +/- 5 K and surface pressures log (k(-1) P cm(-3) K) = 6.0 +/- 0.2. The clump masses span the range 0.3-22 M circle dot assuming a dust temperature T-d similar to 20 K and a dust emissivity kappa(850) = 0.02 cm(2) g(-1). The distribution of clump masses is well characterized by a power law N(M) proportional to M-alpha with alpha = 2.0 0.5 for M > 3.0 M circle dot, indicating a clump mass function steeper than the stellar initial mass function. Significant incompleteness makes determination of the slope at lower masses difficult. A comparison of the submillimeter emission map with an H-2 2.122 mu m survey of the same region is performed. Several new Class 0 sources are revealed and a correlation is found between both the column density and degree of concentration of the submillimeter sources and the likelihood of coincident H-2 shock emission.