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Phys. Rev. D 71, 043502 (2005) [7 pages]

Large-scale magnetic fields from density perturbations

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S. Matarrese1,2, S. Mollerach3, A. Notari4,5, and A. Riotto2
1Dipartimento di Fisica “G. Galilei,” Università di Padova, via Marzolo 8, I-35131 Padova, Italy
2INFN, Sezione di Padova, via Marzolo 8, I-35131 Padova, Italy
3CONICET, Centro Atómico Bariloche, Av. Bustillo 9500, Bariloche, Argentina
4Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa and INFN, Pisa, Italy
5Physics Department, McGill University, 3600 University Road, Montréal, Quebec, Canada H3A 2T8

Received 2 November 2004; published 7 February 2005

We derive the minimal seed magnetic field which unavoidably arises in the radiation and matter eras, prior to recombination, by the rotational velocity of ions and electrons, gravitationally induced by the nonlinear evolution of primordial density perturbations. The resulting magnetic field power spectrum is fully determined by the amplitude and spectral index of density perturbations. The rms amplitude of the seed field at recombination is B≈10-23(λ/Mpc)-2   G, on comoving scales λ≳1   Mpc.

© 2005 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevD.71.043502
DOI:
10.1103/PhysRevD.71.043502
PACS:
98.80.Cq
 
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