Abstract
We present an analysis of the gas outflow energetics from KMOS observations of 529 main-sequence star-forming galaxies at z 1 using broad, underlying Hα and forbid- den lines of [Nii] and [Sii]. Based on the stacked spectra for a sample with median star- formation rates and stellar masses of SFR=7M⊙ / yr and M⋆ =(1.0±0.1)×1010M⊙ respectively, we derive a typical mass outflow rate of ˙Mwind =1–4M⊙ yr−1 and a mass loading of ˙Mwind / SFR=0.2–0.4. By comparing the kinetic energy in the wind with the energy released by supernovae, we estimate a coupling efficiency between the star formation and wind energetics of ǫ 0.03. The mass loading of the wind does not show a strong trend with star-formation rate over the range 2–20M⊙ yr−1, although we identify a trend with stellar mass such that dM/ dt / SFR/M0.26±0.07 ⋆ . Finally, the line width of the broad Hα increases with disk circular velocity with a sub-linear scal- ing relation FWHMbroad /v0.21±0.05. As a result of this behavior, in the lowest mass galaxies (M⋆ < ∼ 1010M⊙), a significant fraction of the outflowing gas should have suf- ficient velocity to escape the gravitational potential of the halo whilst in the highest mass galaxies (M⋆ > ∼ 1010M⊙) most of the gas will be retained, flowing back on to the galaxy disk at later times.
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