Recently there has been mounting evidence for the existence of a cosmological constant (CC). Here we show that cosmic magnetic fields act as a CC, having negative pressure and tending to cause cosmological acceleration. However, if present-day estimates of the intensity of these fields are correct, they would be too weak to be the cause of the acceleration. It is pointed out that large-scale co...

The Cosmic Microwave Background (CMB) physics can be used to constrain the dark energy dynamics: B modes of the polarization of the diffuse CMB emission as well as the polarized signal towards clusters of galaxies are sensitive to the Hubble expansion rate and thus the dark energy abundance in the early stage of cosmic acceleration. The first effect is sourced by gravitational lensing of large ...

The phase of inflationary expansion in the early universe produces superheavy relics in a mass window between 10 GeV and 10 GeV. Decay or annihilation of these superheavy relics can explain the observed ultrahigh energy cosmic rays beyond the GreisenZatsepin-Kuzmin cutoff. We emphasize that the pattern of cosmic ray arrival directions seen by the Pierre Auger observatory will decide between the...

Recently, there has been suggestions that the apparent accelerated expansion of the universe is due not to a cosmological constant, but rather to inhomogeneities in the distribution of matter. In this work, we investigate a specific class of inhomogeneous models that can be solved analytically, namely the dust-dominated Lemâitre-Tolman-Bondi universe models. We show that they do not permit acce...