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Session 66 - Galaxies.
Display session, Thursday, June 11
Atlas Ballroom,
We present a subkiloparsec-scale investigation of the radial profiles of molecular gas, which is the fundamental fuel for recent star formation in galaxies. Given the arcminute-scale resolution and incomplete sampling of existing single-dish surveys of galaxies, little is known about the details of the radial profiles of molecular gas in galaxies, except that the central kiloparsecs of spiral galaxies tend to have higher gas surface densities than do their surrounding disks. Here, we use the 6-9\arcsec\ resolution images from the ongoing BIMA Survey of CO J = (1-0) emission from 44 nearby spiral galaxies to determine the radial profiles of molecular gas in galaxies on size scales of small associations of giant molecular clouds out to 5-10 kpc diameters. The BIMA Survey, undertaken to study the role of molecular gas in the evolution of spiral galaxies, is the first systematic imaging survey of the CO emission from the centers and disks of nearby spiral galaxies on these size scales. We use preliminary observations from the BIMA survey to clarify under what circumstances molecular gas is centrally peaked, flat, ring-shaped, or depressed on sub-kiloparsec scales. We also use these observations to determine if, as for the stellar surface densities, the radial distributions of molecular surface density are well described by exponential disks; this is a fundamental issue in understanding the evolution of star formation in galaxies.
