Interstellar turbulence driving by galactic spiral shocks

Chang Goo Kim, Woong Tae Kim, Eve Charis Ostriker

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

Spiral shocks are potentially a major source of turbulence in the interstellar medium. To address this problem quantitatively, we use numerical simulations to investigate gas flow across spiral arms in vertically stratified, self-gravitating, magnetized models of galactic disks. Our models are isothermal, quasi-axisymmetric, and local in the quasi-radial direction while global in the vertical direction. We find that a stellar spiral potential perturbation promptly induces a spiral shock in the gas flow. For vertically stratified gas disks, the shock front in the radialvertical plane is in general curved, and never achieves a steady state. This behavior is in sharp contrast to spiral shocks in two-dimensional (thin) disks, which are generally stationary. The nonsteady motions in our models include large-amplitude quasi-radial flapping of the shock front. This flapping feeds random gas motions on the scale of the vertical disk thickness, which then cascades to smaller scales. The induced gas velocity dispersion in quasi-steady state exceeds the sonic value for a range of shock strengths, suggesting that spiral shocks are indeed an important generator of turbulence in disk galaxies.

Original languageEnglish (US)
Pages (from-to)L13-L16
JournalAstrophysical Journal
Volume649
Issue number1 II
DOIs
StatePublished - Sep 20 2006

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Galaxies: ISM
  • ISM: kinematics and dynamics
  • Instabilities
  • MHD
  • Methods: numerical
  • Turbulence

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