The SAMI Galaxy Survey: extraplanar gas, galactic winds, and their
  association with star formation history
  We investigate a sample of 40 local, main-sequence, edge-on disc galaxies
using integral field spectroscopy with the Sydney-AAO Multi-object Integral
field spectrograph (SAMI) Galaxy Survey to understand the link between
properties of the extraplanar gas and their host galaxies. The kinematics
properties of the extraplanar gas, including velocity asymmetries and increased
dispersion, are used to differentiate galaxies hosting large-scale galactic
winds from those dominated by the extended diffuse ionized gas. We find rather
that a spectrum of diffuse gas-dominated to wind dominated galaxies exist. The
wind-dominated galaxies span a wide range of star formation rates ($-1 \lesssim
\log({\rm SFR/M_{\odot} yr^{-1}}) \lesssim 0.5$) across the whole stellar mass
range of the sample ($8.5 \lesssim \log({\rm M_{*}/M_{\odot}}) \lesssim 11$).
The wind galaxies also span a wide range in SFR surface densities ($10^{-3}
\textrm{--} 10^{-1.5}\rm~M_{\odot} ~yr^{-1}~kpc^{-2}$) that is much lower than
the canonical threshold of $\rm0.1~M_{\odot} ~yr^{-1}~kpc^{-2}$. The wind
galaxies on average have higher SFR surface densities and higher $\rm
H\delta_A$ values than those without strong wind signatures. The enhanced $\rm
H\delta_A$ indicates that bursts of star formation in the recent past are
necessary for driving large-scale galactic winds. We demonstrate with Sloan
Digital Sky Survey data that galaxies with high SFR surface density have
experienced bursts of star formation in the recent past. Our results imply that
the galactic winds revealed in our study are indeed driven by bursts of star
formation, and thus probing star formation in the time domain is crucial for
finding and understanding galactic winds.
