Related papers: The problem of small angular scale structure in th…
Precise measurements of the energy spectra of cosmic rays (CRs) show various kinds of features deviating from single power-laws, which give very interesting and important implications on their origin and propagation. Previous measurements…
We study the anisotropies on large angular scales which can be present in the flux of cosmic rays reaching the Earth from a population of extragalactic sources, focusing on the energy range between the second knee and the ankle. In this…
Several anomalies have been identified which may imply a breakdown of the statistical isotropy of the cosmic microwave background (CMB). In particular, an anomalous alignment of the quadrupole and octopole and a hemispherical power…
Cosmic strings can arise in hidden sector models with a spontaneously broken Abelian symmetry group. We have studied the couplings of the Standard Model fields to these so-called dark strings in the companion paper. Here we survey the…
The cosmic microwave background anisotropies produced by active seeds, such as topological defects, have been computed recently for a variety of models by a number of authors. In this paper we show how the generic features of the…
The properties of cosmic strings have been investigated in detail for their implications in early-universe cosmology. Although many variations of the basic structure have been discovered, with implications for both the microscopic and…
In a recent paper we considered the possibility of a scalar field providing an explanation for the cosmic acceleration. Our model had the interesting properties of attractor-like behavior and having its parameters of O(1) in Planck units.…
We present a self-contained summary of the theory of linear cosmological perturbations. We emphasize the effect of the six parameters of the minimal cosmological model, first, on the spectrum of Cosmic Microwave Background temperature…
Within a string cosmology context, the large scale temperature anisotropies may arise from the contribution of seeds to the metric fluctuations. We study the cases of electromagnetic and axion seeds. We find that massless or very light…
Anisotropy is very important to understand cosmic ray (CR) source and interstellar environment. The theoretical explanation of cosmic rays anisotropy from experiments remains challenging and even puzzling for a long time. In this paper, by…
The cosmic microwave background (CMB) anisotropy possesses the remarkable property that its power is strongly suppressed on large angular scales. This observational fact can naturally be explained by cosmological models with a non-trivial…
We consider a scenario in which primordial scalar perturbations are generated when complex conformal scalar field rolls down its negative quartic potential. Initially, these are the perturbations of the phase of this field; they are…
The large-scale dipolar structure in the arrival directions of ultra-high-energy cosmic rays with energies above $8\,$EeV observed by the Pierre Auger Collaboration is a well-established anisotropy measurement. This anisotropy is understood…
These lecture notes discuss several topics in the physics of cosmic structure formation starting from the evolution of small-amplitude fluctuations in the radiation-dominated era. The topics include relativistic cosmological perturbation…
In the inflationary scenarios suggested by string theory, the vacuum fluctuations of the electromagnetic field can be amplified by the time-evolution of the dilaton background, and can grow large enough to explain both the origin of the…
The genuine quantum gravity effects can already be around us. It is likely that the observed large-angular-scale anisotropies in the microwave background radiation are induced by cosmological perturbations of quantum-mechanical origin. Such…
Considering the observed anisotropy in cosmic microwave background radiation ($\Delta T/T \leq 10^{-4}$) an upper limit on the electric charge asymmetry over a cosmological scale is found which is several orders more stringent than those…
Models of structure formation with a cosmological constant $\Lambda$ provide a good fit to the observed power spectrum of galaxy clustering. However, they suffer from several problems. Theoretically, it is difficult to understand why the…
An introduction to topological defects in cosmology is given. We discuss their possible relevance for structure formation. Especial emphasis is given on the signature of topological defects in the spectrum of anisotropies in the cosmic…
The observed angular correlation function of the cosmic microwave background has previously been reported to be anomalous, particularly when measured in regions of the sky uncontaminated by Galactic emission. Recent work by Efstathiou et…