2005. The American Astronomical Society. All rights reserved. Printed in U.S.A. GALAXY FORMATION AND COSMIC-RAY ACCELERATION IN A MAGNETIZED UNIVERSE

We study the linear magnetohydrodynamic behavior of a Newtonian cosmology with a viscous magnetized fluid of finite conductivity and generalize the Jeans instability criterion. The presence of the field favors the anisotropic collapse of the fluid, which in turn leads to further magnetic amplification and to enhanced current-sheet formation in the plane normal to the ambient magnetic field. When the currents exceed a certain threshold, the resulting electrostatic turbulence can dramatically amplify the resistivity of the medium (anomalous resistivity). This could trigger strong electric fields and subsequently the acceleration of ultra–high-energy cosmic rays during the formation of protogalactic structures. Subject headings: acceleration of particles — galaxies: formation — large-scale structure of universe — magnetic fields — turbulence A wide variety of astrophysical and cosmological problems are currently interpreted on the basis of gravitational instability. The current large-scale structure and galactic evolution theories are some of the best known examples. Relatively few of the available studies, however, consider the role of magnetic fields