The Gas–Star Formation Cycle in Nearby Star-forming Galaxies. II. Resolved Distributions of CO and Hα Emission for 49 PHANGS Galaxies

The relative distribution of molecular gas and star formation in galaxies gives insight into the physical processes timescales cycle between stars. In this work, we track spatial configuration CO H$\alpha$ emission at high resolution each our galaxy targets, use these measurements to quantify distributions regions different evolutionary stages formation: from without traced by star-forming gas, HII regions. large sample, drawn Physics High Angular Nearby GalaxieS ALMA narrowband (PHANGS-ALMA PHANGS-H$\alpha$) surveys, spans a wide range stellar mass morphological types, allowing us investigate dependencies gas-star on global properties. At 150 pc, incidence shows dependence Hubble type over radial probed. Massive and/or earlier-type exhibit significant reservoir H$\alpha$, while lower-mass harbor substantial that may have dispersed their birth clouds or formed low-mass, more isolated clouds. Galactic structures add further layer complexity emission. Trends properties are visible only when observed scale is $\ll$ 500 reflecting critical requirement distinguish process.