Molecular outflows in local galaxies: Method comparison and a role of intermittent AGN driving.

We report new detections and limits from a NOEMA and ALMA CO(1-0) search for molecular outflows in 13 local galaxies with high FIR surface brightness, and combine with results from the literature. CO line ratios and outflow structure provide some constraints on the conversion from observables to quantities such as molecular mass outflow rates. Ratios between outflow emission in higher J CO transitions and in CO(1-0) typically are consistent with excitation Ri1 ~150km/s outflows, and non-matches can be plausibly ascribed to outflow geometry and SNR. For 12 bright ULIRGs with detailed OH-based outflow modeling, CO outflows are detected in all but one. Outflow masses, velocities, and sizes for these 11 sources agree well between the two methods, and modest remaining differences may relate to the different but overlapping regions sampled by CO emission and OH absorption. Outflow properties correlate better with AGN luminosity and with bolometric luminosity than with FIR surface brightness. The most massive outflows are found for systems with current AGN activity, but significant outflows in non-AGN systems must relate to star formation or to AGN activity in the recent past. We report scaling relations for the increase of outflow mass, rate, momentum rate, and kinetic power with bolometric luminosity. Short ~10^6yr flow times and some sources with resolved multiple outflow episodes support a role of intermittent driving, likely by AGN. (abridged)