Global Star Formation Efficiency of Local Galaxies

This study presents the global star formation efficiency (SFE) of 272 local star-forming galaxies based on the HI gas mass, stellar mass, star formation rate (SFR), and morphology. The SFE increases as the stellar mass increases while the specific SFR decreases. The SFE is enhanced for galaxies with large Ha equivalent widths, which is primarily due to the large SFR, not due to the large available amount of gas. The SFE is also enhanced by a factor of similar to 2 for merging systems compared to the normal spirals, showing that the merger-induced high pressure and density environment are crucial for the active star formation. Based on the SFR scaling relation, I present a SFR calibration formula using the HI gas mass.