Related papers: Entropy Perturbations due to Cosmic Strings
The evolution of perturbations is a crucial part of the phenomenology of the dark sector cosmology. We advocate parameterizing these perturbations using equations of state for the entropy perturbation and the anisotropic stress. For small…
We consider the evolution of an initially FLRW universe after the formation of a long, straight, cosmic string with arbitrary tension and mass per unit length. The birth of the string sources scalar and tensor-type perturbations in the…
The Cosmic Microwave Background (CMB) fluctuations at very small angular scales (less than $10'$) induced by matter sources are computed in a simplified way. The result corrects a previous formula appearing in the literature. The small…
We estimate the amount of vorticity generated at second order in cosmological perturbation theory from the coupling between first order energy density and non-adiabatic pressure, or entropy, perturbations. Assuming power law input spectra…
We study effects of the cosmic string in the D-term inflation model on the cosmic microwave background (CMB) anisotropy. In the D-term inflation model, gauged cosmic string is usually formed, which may significantly affect the CMB…
We study the impact of kinks on the cosmic microwave background (CMB) anisotropies generated by cosmic string networks. To do so, we extend the Unconnected Segment Model to describe the stress-energy tensor of a network of cosmic strings…
Long-wavelength gravitational waves can induce significant temperature anisotropy in the cosmic microwave background. Distinguishing this from anisotropy induced by energy density fluctuations is critical for testing inflationary cosmology…
Non-linear evolution of cosmological energy density fluctuations triggers deviations from Gaussianity in the temperature distribution of the cosmic microwave background. A method to estimate these deviations is proposed. N-body simulations…
We make some observations regarding string/black hole correspondence with a view to understanding the nature of the quantum degrees of freedom of a black hole in string theory. In particular, we compare entropy change in analogous string…
Zero-point fluctuations in the background of a cosmic string provide an opportunity to study the effects of topology in quantum field theory. We use a scattering theory approach to compute quantum corrections to the energy density of a…
Global topological defects produce nonzero stress-energy throughout spacetime, and as a result can have observable gravitational influence on surrounding matter. Gravitational effects of global strings are used to place bounds on their…
We consider the effect of string inhomogeneities on the time dependent background of Brane Gas Cosmology. We derive the equations governing the linear perturbations of the dilaton-gravity background in the presence of string matter sources.…
We study how the presence of world-sheet currents affects the evolution of cosmic string networks, and their impact on predictions for the cosmic microwave background (CMB) anisotropies generated by these networks. We provide a general…
The combination of detections of anisotropy in the Cosmic Microwave Background radiation and observations of the large-scale distribution of galaxies probes the primordial density fluctuations of the universe on spatial scales varying by…
The spontaneous loss of angular momentum of a spinning cosmic string due to particle emission is discussed. The rate of particle production between two assymptotic spacetimes: the spinning cosmic string spacetime in the infinite past and a…
In theories with cosmic strings, a small fraction of string loops may collapse to form black holes. In this Letter, various constraints on such models involving black holes are considered. Hawking radiation from black holes, gamma and…
Photons can gravitationally scatter off a cosmic string loop and gain or lose energy. We consider the spectral distortion induced by cosmic string loops placed in an ambient thermal bath of photons. The fractional deviation from a thermal…
Recent measurements of the Cosmic Microwave Background Anisotropy have provided evidence for the presence of oscillations in the angular power spectrum. These oscillations are a wonderful confirmation of the standard cosmological scenario…
In this note we investigate the effects of perturbations in a dark energy component with a constant equation of state on large scale cosmic microwave background anisotropies. The inclusion of perturbations increases the large scale power.…
Towards the end of the brane inflationary epoch in the brane world, cosmic strings (but not texture, domain walls or monopoles) are copiously produced during brane collision. These cosmic strings are D$p$-branes with $(p-1)$ dimensions…