Understanding galaxy outflows as the product of unstable turbulent support

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The interstellar medium is a multiphase gas in which turbulent support is as important as thermal pressure. Sustaining this configuration requires both continuous turbulent stirring and continuous radiative cooling to match the decay of turbulent energy. While this equilibrium can persist for small turbulent velocities, if the one-dimensional velocity dispersion is larger than ≈35 km s-1, the gas moves into an unstable regime that leads to rapid heating. I study the implications of this turbulent runaway, showing that it causes a hot gas outflow to form in all galaxies with a gas surface density above ≈50 M pc-2, corresponding to a star formation rate per unit area of ≈0.1 M yr-1 kpc-2. For galaxies with v esc ≳ 200 km s-1, the sonic point of this hot outflow should lie interior to the region containing cold gas and stars, while for galaxies with smaller escape velocities, the sonic point should lie outside this region. This leads to efficient cold cloud acceleration in higher mass galaxies, while in lower mass galaxies, clouds may be ejected by random turbulent motions rather than accelerated by the wind. Finally, I show that energy balance cannot be achieved at all for turbulent media above a surface density of ≈105 M pc-2.

Original languageEnglish (US)
Article numberL31
JournalAstrophysical Journal Letters
Volume763
Issue number2
DOIs
StatePublished - Feb 1 2013

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outflow
galaxies
products
gas
gases
escape velocity
cold region
cold gas
sustaining
high temperature gases
stirring
star formation rate
energy balance
product
heating
cooling
stars
energy
causes
decay

Keywords

  • galaxies: starburst
  • ISM: jets and outflows
  • ISM: structure

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Understanding galaxy outflows as the product of unstable turbulent support. / Scannapieco, Evan.

In: Astrophysical Journal Letters, Vol. 763, No. 2, L31, 01.02.2013.

Research output: Contribution to journalArticle

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