It is known that, theoretically, the Rees-Sciama effect may cause arbitrarily large additional redshifts in the cosmic microwave background radiation due to transparent expanding voids having sizes comparable with the size of horizon. Therefore, again theoretically, eventual huge voids existing immediately after the recombination may essentially change the predictions of the theory of big bang ...

In this lecture I give an overview of shock acceleration, interactions of high energy cosmic rays with, and propagation through, the background radiation, and the resulting electron-photon cascade. I argue that while the origin of the highest energy cosmic rays is still uncertain, it is not necessary to invoke exotic models such as emission by topological defects to explain the existing data. I...

A simple extension of the minimal supersymmetric standard model which naturally and simultaneously solves the strong CP and μ problems via a PecceiQuinn and a continuous R symmetry is considered. This model is supplemented with hybrid inflation and leptogenesis, but without taking the specific details of these scenarios. It is shown that the Peccei-Quinn field can successfully act as a curvaton...

We formulate a gradual dynamical transition from a power-law inflation era with a scalar field to a radiation era with no scalar field including inhomogeneous perturbations to the FriedmannRobertson-Walker universe. We show that for the cosmic microwave background radiation fluctuations this is excellently approximated by a sudden transition, with application of the Lichnerowicz conditions, bot...

Simple arguments concerning power and acceleration efficiency show that ultra-high energy cosmic rays (UHECRS) with energies > ∼ 10 eV could originate from GRBs. Neutrons formed through photo-pion production processes in GRB blast waves leave the acceleration site and travel through intergalactic space, where they decay and inject a very energetic proton and electron component into intergalacti...

There has been much interest in possible violations of Lorentz invariance, particularly motivated by quantum gravity theories. It has been suggested that a small amount of Lorentz invariance violation (LIV) could turn off photomeson interactions of ultrahigh energy cosmic rays (UHECRs) with photons of the cosmic background radiation and thereby eliminate the resulting sharp steepening in the sp...

We extend the formalism of the relativistic thermal Sunyaev-Zel’dovich effect to the system moving with a velocity ~ β ≡ ~v/c with respect to the cosmic microwave background radiation. In the present formalism, the kinematic Sunyaev-Zel’dovich effect for the cluster of galaxies with a peculiar velocity ~ β is derived in a straightforward manner by the Lorentz boost of the generalized Kompaneets...

General relativity marked the beginning of modern cosmology and it has been at the centre of many of the key developments in this field. In the present review, we discuss the general-relativistic dynamics and perturbations of the standard cosmological model, the Friedmann-Lemaitre universe, and how these can explain and predict the properties of the observable universe. Our aim is to provide an...

The deepest space and ground-based observations find metal-enriched galaxies at cosmic times when the Universe was < 1 Gyr old. These stellar populations had to be preceded by the metal-free first stars, Population III. Recent cosmic microwave background polarization measurements indicate that stars started forming early when the Universe was < ∼ 200 Myr old. Theoretically it is now thought tha...

In this work we re-examine the opacity of the cosmic background radiation to the propagation of extremely high energy cosmic rays. We use the continuous energy loss approximation to provide spectral modification factors for several hypothesized cosmic ray sources. Earlier problems with this approximation are resolved including the effects of resonances other than the ∆. PACS numbers: 96.40,13.8...