Large-area mapping at 850 microns.: II.: Analysis of the clump distribution in the ρ Ophiuchi molecular cloud

We present results from a survey of the central 700 arcmin(2) region of the rho Ophiuchi molecular cloud at 850 mum using the Submillimeter Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope. Using the clump-finding procedure developed by Williams et al., we identify 55 independent objects and compute size, flux, and degree of central concentration. Comparison with isothermal, pressure-confined, self-gravitating Bonnor-Ebert spheres implies that the clumps have internal temperatures of 10-30 K and surface pressures P/k = 10(6-7) K cm(-3), consistent with the expected average pressure in the rho Ophiuchi central region, P/k similar to 2x10(7) K cm(-3). The clump masses span 0.02- 6.3 M-. assuming a dust temperature T-d similar to 20 K and a dust emissivity kappa (850) = 0.01 cm(2) g(-1). The distribution of clump masses is well characterized by a broken power law, N(M) proportional to M-a, with alpha = 1.0-1.5 for M>0.6 M-. and alpha = 0.5 for M less than or equal to0.6 M-., although significant incompleteness may affect the slope at the lower mass end. This mass function is in general agreement with the rho Ophiuchi clump mass function derived at 1.3 mm by Motte et al. The two-point correlation function of the clump separations is measured and reveals clustering on size scales r <3 x10(4) AU with a radial power-law exponent = 0.75.