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Magnetized gravitational waves

Roy Maartens·Christos Tsagas·Carlo Ungarelli
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Abstract

We investigate the influence of cosmic magnetic fields on gravitational wave perturbations, and find exact solutions on large scales. We show that a large-scale magnetic field can generate large-scale non-decaying gravitational waves. In the general case where gravitational waves are generated by other mechanisms, a large-scale magnetic field introduces a new decaying tensor mode and modifies the non-decaying mode. The direct effect of the magnetic field is to damp the gravitational waves, while an indirect magneto-curvature effect can either damp or boost the waves. A magnetic field also leads to a breaking of statistical isotropy, and the magnetic imprint on the tensor spectrum in principle provides a means of detecting a primordial field.

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Roy Maartens, Christos Tsagas, Carlo Ungarelli. 2001-05-19. Magnetized gravitational waves. https://doi.org/10.1103/physrevd.63.123507

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