Primordial Magnetic Fields in Cosmology

Abstract

Magnetic fields have been observed in galaxies, clusters of galaxies and probably in superclusters. While mechanisms exist to generate these in the late universe, it is possible that magnetic fields have existed since very early times. This thesis is concerned with methods to predict the form of such imprints. We review in detail a standard, linearised cosmology before introducing an electromagnetic field. We then consider the intrinsic statistics of the magnetic stresses in two ways, analytically and via static realisations. We construct the power spectra, some of which we present for the first time. At the one- and three-point level we find significant intrinsic non-Gaussianities. Finally we turn to the observable impacts a primordial magnetic field. Assuming coherence, the statistics of the source can be mapped onto the CMB in a simple manner. We demonstrate that our approach is valid by reproducing the signals for Gaussian power law fields on the microwave sky. [ABRIDGED]

PhD Thesis (ICG, University of Portsmouth, May 2006), 178 pages

Cited by in corpus (7)

• The cosmic microwave background temperature bispectrum from scalar perturbations induced by primordial magnetic fields
• Constraints on primordial magnetic fields from magnetically-induced perturbations: current status and future perspectives with LiteBIRD and future ground based experiments
• Probing the Early Universe with the CMB Scalar, Vector and Tensor Bispectrum
• Reduced bispectrum seeded by helical primordial magnetic fields
• LiteBIRD Science Goals and Forecasts: Primordial Magnetic Fields
• Evolution of magnetic fields through cosmological perturbation theory
• Accelerating the Universe with Gravitational Waves