The SAMI Galaxy Survey: Gas velocity dispersions in low-$z$ star-forming
  galaxies and the drivers of turbulence
  We infer the intrinsic ionised gas kinematics for 383 star-forming galaxies
across a range of integrated star-formation rates (SFR $\in [10^{-3}, 10^2]$
M$_\odot$ yr$^{-1}$) at $z \lesssim 0.1$ using a consistent 3D
forward-modelling technique. The total sample is a combination of galaxies from
the SAMI Galaxy Survey and DYNAMO survey. For typical low-$z$ galaxies taken
from the SAMI Galaxy Survey, we find the vertical velocity dispersion
($\sigma_{v, z}$) to be positively correlated with measures of star-formation
rate, stellar mass, HI gas mass, and rotational velocity. The greatest
correlation is with star-formation rate surface density ($\Sigma_\text{SFR}$).
Using the total sample, we find $\sigma_{v, z}$ increases slowly as a function
of integrated star-formation rate in the range SFR $\in$ [$10^{-3}$, 1]
M$_\odot$ yr$^{-1}$ from $17\pm3$ km s$^{-1}$ to $24\pm5$ km s$^{-1}$ followed
by a steeper increase up to $\sigma_{v, z}$ $\sim 80$ km s$^{-1}$ for SFR
$\gtrsim 1$ M$_\odot$ yr$^{-1}$. This is consistent with recent theoretical
models that suggest a $\sigma_{v, z}$ floor driven by star-formation feedback
processes with an upturn in $\sigma_{v, z}$ at higher SFR driven by
gravitational transport of gas through the disc.
