Swinbank, A. M. and Harrison, Chris M. and Tiley, Alfred L. and Johnson, Helen L. and Smail, Ian and Stott, John and Best, Philip N. and Bower, Richard and Bureau, Martin and Cirasuolo, M. and Jarvis, Matt and Magdis, Georgios E. and Sharples, Ray M. and Sobral, David (2019) The energetics of starburst-driven outflows at z ∼ 1 from KMOS. Monthly Notices of the Royal Astronomical Society, 487 (1). 381–393. ISSN 0035-8711
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 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 M⊙ / yr and M⋆ = (1.0 ± 0.1) × 1010 M⊙ respectively, we derive a typical mass outflow rate of \dot{M}_wind = 1-4 M⊙ yr-1 and a mass loading of \dot{M}_wind / 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 ɛ ˜ 0.03. The mass loading of the wind does not show a strong trend with star-formation rate over the range ˜ 2-20 M⊙ yr-1, although we identify a trend with stellar mass such that dM / dt / SFR ∝ M_\star ^{0.26± 0.07}. Finally, the line width of the broad Hα increases with disk circular velocity with a sub-linear scaling relation FWHMbroad ∝ v0.21 ± 0.05. As a result of this behavior, in the lowest mass galaxies (M_\star ≲10^{10} M⊙), 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_\star ≳10^{10} M⊙) most of the gas will be retained, flowing back on to the galaxy disk at later times.