The SAMI Galaxy Survey: impact of star formation and AGN feedback processes on the ionized gas velocity dispersion

We investigate the influence of star formation and instantaneous AGN feedback processes on the ionized gas velocity dispersion in a sample of 1285 emission-line galaxies with stellar masses log (M_*/M_⊙) ≥ 9 from the integral-field spectroscopy SAMI Galaxy Survey. We fit both narrow and broad emission line components using aperture spectra integrated within one effective radius, while ensuring the elimination of velocity differences between the spectra of individual spaxels. Our analysis reveals that 386 (30 galaxies can be adequately described using a single emission component while 356 (28 characterized by high mass, elevated star formation rate surface density, or type-2 AGN-like emissions tend to feature an additional broad emission-line component, leading to their classification as double-component galaxies. We explore the correlations between M_* and gas velocity dispersions, highlighting that the prominence of the broad component significantly contributes to elevating the gas velocity dispersion. Galaxies displaying AGN-like emission based on optical definitions show enhanced gas velocity dispersions. In star-forming galaxies, both stellar mass and star-formation rate surface density substantially contribute to the velocity dispersion of the narrow component. Increased star-forming activity appears to elevate the velocity dispersion of the narrow component. The broad component exhibits a weaker dependence on stellar mass and is primarily driven by galactic outflows. We suggest that strong star forming activity leads to the formation of a broad emission-line component, but the impact on inflating gas velocity dispersion is moderate. On the other hand, AGN-driven outflows appear to be a more important contributor to the elevated velocity dispersion of the ionized gas.