Identification of a fundamental transition in a turbulently supported interstellar medium

Evan Scannapieco, William J. Gray, Liubin Pan

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The interstellar medium (ISM) in star-forming galaxies is a multiphase gas in which turbulent support is at least as important as thermal pressure. Sustaining this configuration requires continuous radiative cooling, such that the overall average cooling rate matches the decay rate of turbulent energy into the medium. Here we carry out a set of numerical simulations of a stratified, turbulently stirred, radiatively cooled medium, which uncover a fundamental transition at a critical one-dimensional turbulent velocity of 35kms -1. At turbulent velocities below 35kms-1, corresponding to temperatures below 105.5 K, the medium is stable, as the time for gas to cool is roughly constant as a function of temperature. On the other hand, at turbulent velocities above the critical value, the gas is shocked into an unstable regime in which the cooling time increases strongly with temperature, meaning that a substantial fraction of the ISM is unable to cool on a turbulent dissipation timescale. This naturally leads to runaway heating and ejection of gas from any stratified medium with a 1D turbulent velocity above 35kms -1, a result that has implications for galaxy evolution at all redshifts.

Original languageEnglish (US)
Article number57
JournalAstrophysical Journal
Volume746
Issue number1
DOIs
StatePublished - Feb 10 2012

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cooling
gas
gases
temperature
galaxies
dissipation
sustaining
heating
timescale
ejection
decay rates
simulation
energy
stars
configurations
rate

Keywords

  • galaxies: evolution
  • galaxies: starburst
  • ISM: structure

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Identification of a fundamental transition in a turbulently supported interstellar medium. / Scannapieco, Evan; Gray, William J.; Pan, Liubin.

In: Astrophysical Journal, Vol. 746, No. 1, 57, 10.02.2012.

Research output: Contribution to journalArticle

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