What drives the velocity dispersion of ionized gas in star-forming galaxies?

We analyse the intrinsic velocity dispersion properties of 648 star-forming galaxies observed by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, to explore the relation of intrinsic gas velocity dispersions with star formation rates (SFRs), SFR surface densities ({Σ _{SFR}}), stellar masses, and stellar mass surface densities ({Σ _{*}}). By combining with high z galaxies, we found that there is a good correlation between the velocity dispersion and the SFR as well as {Σ _{SFR}}. But the correlation between the velocity dispersion and the stellar mass as well as {Σ _{*}} is moderate. By comparing our results with predictions of theoretical models, we found that the energy feedback from star formation processes alone and the gravitational instability alone cannot fully explain simultaneously the observed velocity-dispersion/SFR and velocity-dispersion/{Σ _{SFR}} relationships.