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Particle horizon

About: Particle horizon is a research topic. Over the lifetime, 2096 publications have been published within this topic receiving 69137 citations.


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Journal ArticleDOI
TL;DR: In this paper, a cosmological model in which the universe has its critical density and the gravitational and cosmology "constants"G and Λ are time-dependent is presented.
Abstract: A cosmological model in which the universe has its critical density and the gravitational and cosmological “constants”G and Λ are time-dependent is presented. The model may possibly solve the horizon and monopole problems. It predicts a perpetually expanding universe in whichG increases and Λ decreases with time in a manner consistent with conservation of the energy-momentum tensor. The model also allows the calculation of various cosmological parameters.

144 citations

Journal ArticleDOI
TL;DR: In this paper, the cosmological reconstruction in an anisotropic universe for both the homogeneous and inhomogeneous content of the universe is investigated for Bianchi types I, Bianchi type III, and Kantowski-Sachs models.
Abstract: We investigate the cosmological reconstruction in an anisotropic universe for both the homogeneous and inhomogeneous content of the universe Special attention is given to three interesting cases: Bianchi type I, Bianchi type III, and Kantowski-Sachs models The de Sitter, power-law, and general exponential solutions are assumed for the scale factor in each spatial direction and the corresponding cosmological models are reconstructed Moreover, for the general exponential solutions---from which the de Sitter and power-law solutions may be obtained---we obtain models which reproduce the early Universe (assuming inflation) and the late-time accelerated expanding Universe The models obtained for the late-time Universe are consistent with a known result in the literature where a power-law type correction in $T$ is added to a power-law type of $f(T)$ for guaranteeing the avoidance of the big rip and the big freeze

134 citations

Journal ArticleDOI
TL;DR: In this paper, the authors consider a model of the universe in which the matter content is in the form of discrete islands, rather than a continuous fluid, and find the angular diameter distance, luminosity distance, and redshifts that would be measured by observers in these space-times, using both analytic approximations and numerical simulations.
Abstract: We consider a model of the Universe in which the matter content is in the form of discrete islands, rather than a continuous fluid In the appropriate limits the resulting large-scale dynamics approach those of a Friedmann-Robertson-Walker (FRW) universe The optical properties of such a space-time, however, do not This illustrates the fact that the optical and "average" dynamical properties of a relativistic universe are not equivalent, and do not specify each other uniquely We find the angular diameter distance, luminosity distance, and redshifts that would be measured by observers in these space-times, using both analytic approximations and numerical simulations While different from their counterparts in FRW, the effects found do not look like promising candidates to explain the observations usually attributed to the existence of dark energy This incongruity with standard FRW cosmology is not due to the existence of any unexpectedly large structures or voids in the Universe, but only to the fact that the matter content of the Universe is not a continuous fluid

132 citations

Journal ArticleDOI
TL;DR: In this article, the luminosity distance-redshift relation in a perturbed flat matter-dominated universe is computed, taking into account the presence of cosmological inhomogeneities up to second order in perturbation theory.
Abstract: The luminosity distance-redshift relation is one of the fundamental tools of modern cosmology We compute the luminosity distance-redshift relation in a perturbed flat matter-dominated Universe, taking into account the presence of cosmological inhomogeneities up to second order in perturbation theory Cosmological observations implementing the luminosity distance-redshift relation tell us that the Universe is presently undergoing a phase of accelerated expansion This seems to call for a mysterious Dark Energy component with negative pressure Our findings suggest that the need of a Dark Energy fluid may be challenged once a realistic inhomogeneous Universe is considered and that an accelerated expansion may be consistent with a matter-dominated Universe

128 citations

Journal ArticleDOI
TL;DR: In this paper, the main contribution to axion energy density fluctuations at horizon crossing are those impressed on the axions by the geometry, i.e. by the original adiabatic variations in the radiation field.

127 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202320
202247
20216
202010
201910
201814