We perform a stacking analysis of the neutral Na D \lambda \lambda 5889,5895 Å ISM doublet using the SDSS DR7 spectroscopic data set to probe the prevalence and characteristics of cold ( T \lesssim 10 ^ { 4 } K ) galactic-scale gas flows in local ( 0.025 \leqslant z \leqslant 0.1 ) inactive and AGN-host galaxies across the SFR-M _ { * } plane .
We find low-velocity outflows to be prevalent in regions of high SFRs and stellar masses ( 10 \lesssim log M _ { * } /M _ { \odot } \lesssim 11.5 ) , however we do not find any detections in the low mass ( log M _ { * } /M _ { \odot } \lesssim 10 ) regime .
We also find tentative detections of inflowing gas in high mass galaxies across the star-forming population .
We derive mass outflow rates in the range of 0.14-1.74 M _ { \odot } yr ^ { -1 } and upper limits on inflow rates < 1 M _ { \odot } yr ^ { -1 } , allowing us to place constraints on the mass loading factor ( \eta = \dot { M } _ { \text { out } } /SFR ) for use in simulations of the local Universe .
We discuss the fate of the outflows by comparing the force provided by the starburst to the critical force needed to push the outflow outward , and find the vast majority of the outflows unlikely to escape the host system .
Finally , as outflow detection rates and central velocities do not vary strongly with the presence of a ( weak ) active supermassive black hole , we determine that star formation appears to be the primary driver of outflows at z \sim 0 .