The mass and momentum outflow rates of photoionized galactic outflows
- 12 May 2017
- journal article
- research article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 469 (4), 4831-4849
- https://doi.org/10.1093/mnras/stx1164
Abstract
Galactic outflows are believed to play an important role in regulating star formation in galaxies, but estimates of the outflowing mass and momentum have historically been based on uncertain assumptions. Here, we measure the mass, momentum and energy outflow rates of seven nearby star-forming galaxies using ultraviolet absorption lines and observationally motivated estimates for the density, metallicity, and radius of the outflow. Low-mass galaxies generate outflows faster than their escape velocities with mass outflow rates up to twenty times larger than their star formation rates. These outflows from low-mass galaxies also have momenta larger than provided from supernovae alone, indicating that multiple momentum sources drive these outflows. Only 1–20 per cent of the supernovae energy is converted into kinetic energy, and this fraction decreases with increasing stellar mass, such that low-mass galaxies drive more efficient outflows. We find scaling relations between the outflows and the stellar mass of their host galaxies (M*) at the 2–3σ significance level. The mass-loading factor, or the mass outflow rate divided by the star formation rate, scales as M$$_\ast ^{-0.4}$$ and with the circular velocity as v$$_\mathrm{circ}^{-1.6}$$. The scaling of the mass-loading factor is similar to recent simulations, but the observations are a factor of 5 smaller, possibly indicating that there is a substantial amount of unprobed gas in a different ionization phase. The outflow momenta are consistent with a model where star formation drives the outflow while gravity counteracts this acceleration.
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This publication has 90 references indexed in Scilit:
- Spatially resolved galactic wind in lensed galaxy RCSGA 032727-132609Monthly Notices of the Royal Astronomical Society, 2016
- A VERSATILE FAMILY OF GALACTIC WIND MODELSThe Astrophysical Journal, 2016
- INDIRECT EVIDENCE FOR ESCAPING IONIZING PHOTONS IN LOCAL LYMAN BREAK GALAXY ANALOGSThe Astrophysical Journal, 2015
- Spectral energy distributions of an AKARI-SDSS-GALEX sample of galaxiesAstronomy & Astrophysics, 2011
- The Chemical Composition of the SunAnnual Review of Astronomy and Astrophysics, 2009
- What Shapes the Luminosity Function of Galaxies?The Astrophysical Journal, 2003
- Galactic Stellar and Substellar Initial Mass FunctionPublications of the Astronomical Society of the Pacific, 2003
- The Dust Content and Opacity of Actively Star‐forming GalaxiesThe Astrophysical Journal, 2000
- Physical conditions in the Orion Nebula and an assessment of its helium abundanceThe Astrophysical Journal, 1991
- Wind from a starburst galaxy nucleusNature, 1985