Gravity-driven Turbulence in Galactic Disks

By K. Wada, G. Meurer, C. Norman. 2002

139 citations recorded by the source corpus.

High-resolution, two-dimensional hydrodynamical simulations with a large dynamic range are performed to study the turbulent nature of the interstellar medium (ISM) in galactic disks. The simulations are global, where the self-gravity of the ISM, realistic radiative cooling, and galactic rotation are taken into account. In the analysis undertaken here, feedback processes from the stellar energy source are omitted. We find that the velocity field of the disk in a nonlinear phase shows a steady power-law energy spectrum over 3 orders of magnitude in wavenumber. This implies that the random velocity field can be modeled as fully developed, stationary turbulence. Gravitational and thermal instabilities under the influence of galactic rotation contribute to the formation of the turbulent velocity field. The Toomre effective Q-value, in the nonlinear phase, covers a wide range, and gravitationally stable and unstable regions are distributed patchily in the disk. These results suggest that large-scale galactic rotation coupled with the self-gravity of the gas can be the ultimate energy sources that maintain the turbulence in the local ISM. Our models of turbulent rotating disks are consistent with the velocity dispersion of an extended H I disk in the dwarf galaxy NGC 2915, where there is no prominent active star formation. Numerical simulations show that the stellar bar in NGC 2915 enhances the velocity dispersion, and it also drives spiral arms, as observed in the H I disk.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/5e4f800ae7a636d564f8b072b89815857e5b92f2

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Citations in the corpus

A NEW JEANS RESOLUTION CRITERION FOR (M)HD SIMULATIONS OF SELF-GRAVITATING GAS: APPLICATION TO MAGNETIC FIELD AMPLIFICATION BY GRAVITY-DRIVEN TURBULENCE (2011, background): “Gravity-driven turbulence inside galactic disks in twodimensional (2D), high-resolution simulations by Wada et al. (2002) show comparable values of χ ≈ 1/2 to what we find here.”
Interstellar Turbulence I: Observations and Processes (2004, background): “Simulation codes are finally becoming sophisticated enough to model at least the central regions of differentially rotating galaxies, with simulations of 2 kpc x 2 kpc up to 40962 (Wada & Norman 2001, Wada et al. 2002).”
Physical Processes in the Interstellar Medium (2014, background): “Wada et al. (2002) estimated the energy input resulting from these Newton stress terms.”
The Supernova Rate-Velocity Dispersion Relation in the Interstellar Medium (2005, background): “797 and Wada et al. (2000, 2002) investigated the evolution of thermal and gravitational instabilities (TI and GI, respectively) in galactic disks.”
FORMATION OF MASSIVE GALAXIES AT HIGH REDSHIFT: COLD STREAMS, CLUMPY DISKS, AND COMPACT SPHEROIDS (2009, background): “One particular mechanism of this sort for generating velocity dispersion in the disk is the gravitational en- counters between the bound disk clumps (see Wada et al. 2002; Agertz et al. 2008; Tasker & Tan 2009).”
MORPHOLOGICAL QUENCHING OF STAR FORMATION: MAKING EARLY-TYPE GALAXIES RED (2009, background): “The ISM turbulence in star-forming spiral galaxies is mostly triggered by gravitational instabilities and starformation feedback (Elmegreen et al. 2003; Wada et al. 2002; Tasker & Bryan 2008; Agertz et al. 2009).”
ISM properties in hydrodynamic galaxy simulations: turbulence cascades, cloud formation, role of gravity and feedback (2010, methodology): “Wada et al. (2002) already mentioned that the properties of turbulent motions in their galaxy models were consistent with an inverse cascade of turbulence.”