Statistical Study of the Star Formation Efficiency in Bars: Is Star Formation Suppressed in Gas-rich Bars?

Abstract The dependence of the star formation efficiency (SFE) on galactic structures—especially whether SFE in bar region is lower than those other regions—has recently been debated. We report SFEs 18 nearby gas-rich massive star-forming barred galaxies with large apparent major axes (≧75″). statistically measure by distinguishing center, end, and regions for first time. molecular gas surface density derived from archival CO(1–0) and/or CO(2–1) data assuming a constant CO-to-H 2 conversion factor ( α CO ), rate linear combination far-UV mid-IR intensities. angular resolution 15″, which corresponds to 0.3–1.8 kpc. find that ratio disk was systematically unity (typically 0.6–0.8), means suppressed. Our results are inconsistent similar recent statistical studies, have reported tends be independent structures. This inconsistency can attributed differences definitions region, spatial resolutions, , sample galaxies. Furthermore, we negative correlation between velocity width spectrum, consistent idea dynamical effects—such as strong shocks, shears, fast cloud–cloud collisions caused noncircular motion bar—result low SFE.