# The energetics of starburst-driven outflows at z=1 from KMOS

## TL;DR

This study analyzes the energetics of starburst-driven outflows in 529 star-forming galaxies at z~1, revealing how outflow rates relate to galaxy mass and star formation, and implications for gas retention.

## Contribution

It provides the first detailed analysis of outflow energetics at z~1 using KMOS data, highlighting the relation between outflow properties and galaxy mass.

## Key findings

- Mass outflow rate of 1-4 Mo/yr in typical galaxies.
- Mass loading factor of 0.2-0.4, weakly dependent on SFR.
- Outflows in low-mass galaxies can escape, while high-mass galaxies retain gas.

## Abstract

We present an analysis of the gas outflow energetics of 529 main-sequence star-forming galaxies at z~1 using KMOS observations of the broad, underlying H-alpha and forbidden lines of [N II] and [S II]. Based on the stacked spectra for a sample with median star-formation rates and stellar masses of SFR ~ 7 Mo/yr and M* = (1.0+/-0.1)x10^10 Mo respectively, we derive a typical mass outflow rate of dM/dt = 1-4 Mo/yr and a mass loading of dM/dt/SFR = 0.2--0.4. The mass loading of the wind does not show a strong trend with star-formation rate over the range SFR ~ 2--20 Mo/yr, although we identify a trend with stellar mass such that dM/dt/SFR ~ M*^(0.26+/-0.07). Finally, we find that the line width of the broad H-alpha increases with disk circular velocity with a sub-linear scaling relation FWHM_broad ~ v^(0.21+/-0.05). As a result of this behavior, in the lowest mass galaxies (M* < 10^10 Mo), a significant fraction of the outflowing gas should have sufficient velocity to escape the gravitational potential of the halo whilst in the highest mass galaxies (M* > 10^10 Mo) most of the gas will be retained, flowing back on to the galaxy disk at later times.