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

Research output: Contribution to journalJournal article

Forthcoming
  • A. M. Swinbank
  • Chris M. Harrison
  • Alfred L. Tiley
  • Helen L. Johnson
  • Ian Smail
  • John Stott
  • Philip N. Best
  • Richard Bower
  • Martin Bureau
  • M. Cirasuolo
  • Matt Jarvis
  • Georgios E. Magdis
  • Ray M. Sharples
  • David Sobral
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<mark>Journal publication date</mark>9/05/2019
<mark>Journal</mark>Monthly Notices of the Royal Astronomical Society
Publication statusAccepted/In press
Original languageEnglish

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.