Large-scale galactic turbulence: can self-gravity drive the observed HI velocity dispersions?
Journal article, 2009

Observations of turbulent velocity dispersions in the HI component of galactic discs show a characteristic floor in galaxies with low star formation rates and within individual galaxies the dispersion profiles decline with radius. We carry out several high-resolution adaptive mesh simulations of gaseous discs embedded within dark matter haloes to explore the roles of cooling, star formation, feedback, shearing motions and baryon fraction in driving turbulent motions. In all simulations the disc slowly cools until gravitational and thermal instabilities give rise to a multiphase medium in which a large population of dense self-gravitating cold clouds are embedded within a warm gaseous phase that forms through shock heating. The diffuse gas is highly turbulent and is an outcome of large-scale driving of global non-axisymmetric modes as well as cloud-cloud tidal interactions and merging. At low star formation rates these processes alone can explain the observed HI velocity dispersion profiles and the characteristic value of similar to 10 km s(-1) observed within a wide range of disc galaxies. Supernovae feedback creates a significant hot gaseous phase and is an important driver of turbulence in galaxies with a star formation rate per unit area greater than or similar to 10(-3) M(circle dot) yr(-1) kpc(-2).


O. Agertz

University of Zürich

G. Lake

University of Zürich

R. Teyssier

The French Alternative Energies and Atomic Energy Commission (CEA)

University of Zürich

B. Moore

University of Zürich

L. Mayer

Swiss Federal Institute of Technology in Zürich (ETH)

University of Zürich

Alessandro Romeo

Chalmers, Department of Radio and Space Science, Radio Astronomy and Astrophysics

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 392 1 294-308

Subject Categories

Astronomy, Astrophysics and Cosmology


Basic sciences



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