Related papers: Global textures and the Doppler peaks
It is by now well established that the magnitude of the two-point angular-correlation function of the cosmic microwave background temperature anisotropies is anomalously low for angular separations greater than about 60 degrees. Physics…
The observed power spectrum of the cosmic microwave background (CMB) is consistent with inflationary cosmology, which predicts a nearly scale-invariant power spectrum of quantum fluctuations of the inflaton field as they exit the Hubble…
We investigate the effects of the presence of relic classical superhorizon inhomogeneities during inflation. This superhorizon inhomogeneity appears as a gradient locally and picks out a preferred direction. Quantum fluctuations on this…
The fluctuations of the cosmic microwave background (CMB) are investigated for a small open universe, i.e., one which is periodically composed of a small fundamental cell. The evolution of initial metric perturbations is computed using the…
We perform detailed calculations of cosmic microwave background (CMB) anisotropies in a CDM-dominated open universe with primordial adiabatic density perturbations for a variety of reionization histories. We show that to a great extent, the…
Inflation drives quantum fluctuations beyond the Hubble horizon, freezing them out before the small-scale modes re-enter during the radiation dominated epoch, and subsequently decay, while large-scale modes re-enter later during the matter…
We investigate cosmological structure formation seeded by topological defects which may form during a phase transition in the early universe. First we derive a partially new, local and gauge invariant system of perturbation equations to…
The amplitude of the second peak in the angular power spectrum of the cosmic microwave background radiation is constrained to be small by recent experiments like Boomerang. This is surprising in the context of the LambdaCDM model, which…
We develop a model for correlations of cosmic microwave background anisotropy on the largest angular scales, based on standard causal geometrical relationships in slow-roll inflation. Unlike standard models based on quantized field modes,…
While large scale cosmic microwave background (CMB) anisotropies involve a combination of the scalar and tensor fluctuations, the scalar amplitude can be independently determined through the CMB-galaxy cross-correlation. Using recently…
A dark energy scalar (or a function of the Ricci scalar) coupled with the derivative to the matter fields will violate the $CPT$ symmetry during the expansion of the Universe. This type of cosmological $CPT$ violation helps to generate the…
Weak gravitational lensing by foreground density perturbations generates a gradient mode in the shear of background images. In contrast, cosmological tensor perturbations induce a non-zero curl mode associated with image rotations. In this…
We calculate the angular power spectrum of the galactic synchrotron radiation induced by the small scale fluctuations of the magnetic field and the cosmic ray electron density. Using the observed interstellar magnetic field spectrum, which…
Recent work has emphasised the importance of vector and tensor contributions to the large scale microwave anisotropy fluctuations produced by cosmic defects. In this paper we provide a general discussion of these contributions, and how…
We present a new model for the formation of spherically symmetric clusters in an expanding Universe. Both the Universe and the collapsing cluster are governed by the same pressure less fluid equations for which a uniform initial density…
Both the Wilkinson Microwave Anisotropy Probe (WMAP) and Planck observations reported the hemispherical asymmetry of the cosmic microwave background (CMB) temperature fluctuation. The hemispherical asymmetry might be stemmed from the…
In this paper we examine the change in the estimated spatial power spectra at decoupling due to the effects of our clumpy universe which modify observational distances. We find that scales at decoupling can be significantly underestmated in…
Scaling arguments are used to constrain the angular spectrum of distortions on boundaries of macroscopic causal diamonds, produced by Planck-scale vacuum fluctuations of causally-coherent quantum gravity. The small-angle spectrum of…
Modern cosmology has now emerged as a testing ground for theories beyond the standard model of particle physics. In this paper, we consider quantum fluctuations of the inflaton scalar field on certain noncommutative spacetimes and look for…
We study the topology generated by the temperature fluctuations of the Cosmic Microwave Background (CMB) radiation, as quantified by the number of components and holes, formally given by the Betti numbers, in the growing excursion sets. We…