2001/06/30 by Chiara Caprini, Ruth Durrer · 3 citations
Earth and Planetary Sciences · Physics and Astronomy · #Cosmology and Gravitation Theories #Geophysics and Gravity Measurements #Solar and Space Plasma Dynamics #astro-ph #gr-qc #hep-ph
paper · pdf · doi:10.1103/physrevd.65.023517
published as Phys.Rev.D65:023517,2001 · 11pages 2 figures Replaced with the significantly expanded version accepted for publication in PRD. More detailed explanations, same conclusions
arxiv created 2001/10/01 · openalex publication_date 2001/12/26 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We compute the gravity waves induced by anisotropic stresses of stochastic primordial magnetic fields. The nucleosynthesis bound on gravity waves is then used to derive a limit on the magnetic field amplitude as a function of the spectral index. The obtained limits are extraordinarily strong: If the primordial magnetic field is produced by a causal process, leading to a spectral index n>~2 on superhorizon scales, galactic magnetic fields produced at the electroweak phase transition or earlier have to be weaker than B_\ensuremathλ<~10^\ensuremath-27 G. If they are induced during an inflationary phase (reheating temperature T\ensuremath∼1015 GeV) with a spectral index n\ensuremath∼0, the magnetic field has to be weaker than B_\ensuremathλ<~10^\ensuremath-39 G. Only very red magnetic field spectra, n\ensuremath∼\ensuremath-3, are not strongly constrained. We also find that a considerable amount of the magnetic field energy is converted into gravity waves. The gravity wave limit derived in this work rules out most of the proposed processes for primordial seeds for the large scale magnetic fields observed in galaxies and clusters.