The Kelvin-Helmholtz instability in an expanding universe and its effect on dark matter
GRECO, Institut d'Astrophysique de Paris, CNRS, 98bis Boulevard Arago, 75014 Paris, France
2 Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 2EG, UK
Corresponding author: K. A. Malik, email@example.com
Accepted: 12 May 2003
We extend the Kelvin-Helmholtz instability to an expanding background. We study the evolution of a non-viscous irrotational fluid and find that for wavelengths much smaller than the Hubble scale small perturbations of the fluid are unstable for wavenumbers larger than a critical value. We then apply this result in the early universe, treating cold dark matter as a classical fluid with vanishing background pressure.
Key words: instabilities / cosmology: theory / cosmology: dark matter
© ESO, 2003