Annu. Rev. Astron. Astrophys. 2004. 42: 275-316
Copyright © 2004 by . All rights reserved

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INTERSTELLAR TURBULENCE II: IMPLICATIONS AND EFFECTS

John Scalo

Department of Astronomy, University of Texas, Austin, Texas 78712

Bruce G. Elmegreen

IBM Research Division, Yorktown Heights, New York 10598


Abstract. Interstellar turbulence has implications for the dispersal and mixing of the elements, cloud chemistry, cosmic ray scattering, and radio wave propagation through the ionized medium. This review discusses the observations and theory of these effects. Metallicity fluctuations are summarized, and the theory of turbulent transport of passive tracers is reviewed. Modeling methods, turbulent concentration of dust grains, and the turbulent washout of radial abundance gradients are discussed. Interstellar chemistry is affected by turbulent transport of various species between environments with different physical properties and by turbulent heating in shocks, vortical dissipation regions, and local regions of enhanced ambipolar diffusion. Cosmic rays are scattered and accelerated in turbulent magnetic waves and shocks, and they generate turbulence on the scale of their gyroradii. Radio wave scintillation is an important diagnostic for small scale turbulence in the ionized medium, giving information about the power spectrum and amplitude of fluctuations. The theory of diffraction and refraction is reviewed, as are the main observations and scintillation regions.


Table of Contents

INTRODUCTION

TURBULENCE AND CHEMICAL INHOMOGENEITY
Metallicity Fluctuations: Observations
How Large Should Metallicity Fluctuations Be?
Methods of Analysis
How Do The Metals Enter the Flow?
Turbulent Concentration of Dust Grains
Turbulent Washout of Radial Abundance Gradients

EFFECTS OF TURBULENCE ON INTERSTELLAR CHEMISTRY
Turbulent Transport of Chemical Species
Turbulent Heating

COSMIC RAY SCATTERING AND ACCELERATION IN A TURBULENT INTERSTELLAR MEDIUM
Cosmic Ray Scattering in Magnetic Waves
Other Scattering Mechanisms
Cosmic Ray Acceleration
Generation of Turbulence by Cosmic Rays

RADIO WAVE SCINTILLATION AS A DIAGNOSTIC FOR ISM TURBULENCE
Theory of Diffraction and Refraction in the ISM
Observations
Summary of Scintillation

SUMMARY AND REFLECTIONS

REFERENCES

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