Entropy perturbations and large-scale magnetic fields

Abstract

An appropriate gauge-invariant framework for the treatment of magnetized curvature and entropy modes is developed. It is shown that large-scale magnetic fields, present after neutrino decoupling, affect curvature and entropy perturbations. The evolution of different magnetized modes is then studied across the matter-radiation transition both analytically and numerically. From the observation that, after equality (but before decoupling) the (scalar) Sachs-Wolfe contribution must be (predominantly) adiabatic, constraints on the magnetic power spectra are deduced. The present results motivate the experimental analysis of more general initial conditions of CMB anisotropies (i.e. mixtures of magnetized adiabatic and isocurvature modes during the pre-decoupling phase). The role of the possible correlations between the different components of the fluctuations is partially discussed.

43 pages, 9 figures

References in corpus (2)

• CMB anisotropies from primordial inhomogeneous magnetic fields
• Correlated adiabatic and isocurvature CMB fluctuations in the wake of the WMAP

Cited by in corpus (10)

• Cosmology with inhomogeneous magnetic fields
• Effects of a Primordial Magnetic Field on Low and High Multipoles of the CMB
• Inflation-Produced Magnetic Fields in R^n F^2 and I F^2 models
• Faraday rotation, stochastic magnetic fields and CMB maps
• CMB anisotropies due to cosmological magnetosonic waves
• Tight coupling expansion and fully inhomogeneous magnetic fields
• Possible extensions of the standard cosmological model: anisotropy, rotation, and magnetic field
• Semi-analytical approach to magnetized temperature autocorrelations
• Generalized CMB initial conditions with pre-equality magnetic fields
• Why CMB physics?