Resumen

ZANNIAS, T. Aspects of cosmic magnetism. Rev. mex. fis. [online]. 2007, vol.53, suppl.2, pp.146-156. ISSN 0035-001X.

In this paper, after a brief review of the current observational evidences regarding the phenomenon of cosmic magnetism, we discuss the problems associated with the generation of electromagnetic fields by conducting fluid flows. In particular , we examine the electromagnetic field generated by a conducting fluid flow in the so-called magnetohydrodynamical (MHD) regime in the non-relativistic and general relativistic limit. Our efforts are directed at the status of Cowlings theorem for the two limits. We show that electromagnetic fields generated by conducting fluids in an arbitrary spacetime (M, g) are influenced by the conducting and kinematical variables defining the fluid flow, but also influenced by the curvature and topology of the underlying spacetime. For the particular case of spatially homogeneous and isotropic backgrounds or stationary-axially symmetric circular spacetimes, we show that the dynamical equations describing electromagnetics fields generated by particular conducting flows reduce to a form structurally similar to the non-relativistic limit. Despite this siplification, the issue whether axially symmetric conducting fluid flows can maintain an axisymmetric magnetic field against Ohmic dissipation is still open.

Palabras llave : Magnetohydrodynamics; compact objects; gravitation.

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