Anisotropy in a non-singular bounce
TLDR
In this paper, Singh et al. studied the evolution of anisotropies in a model where an ekpyrotic phase of contraction is followed by domination of a Galileon-type Lagrangian which generates a non-singular bounce.Abstract:
Following recent claims relative to the question of large anisotropy production in regular bouncing scenarios, we study the evolution of such anisotropies in a model where an ekpyrotic phase of contraction is followed by domination of a Galileon-type Lagrangian which generates a non-singular bounce. We show that the anisotropies decrease during the phase of ekpyrotic contraction (as expected) and that they can be constrained to remain small during the non-singular bounce phase (a non-trivial result). Specifically, we derive the e-folding number of the phase of ekpyrotic contraction which leads to a present-day anisotropy in agreement with current observational bounds. Communicated by P Singhread more
Citations
More filters
Journal ArticleDOI
Modified gravity theories on a nutshell: Inflation, bounce and late-time evolution
TL;DR: In this paper, the authors systematically review some standard issues and also the latest developments of modified gravity in cosmology, emphasizing on inflation, bouncing cosmology and late-time acceleration era.
Journal ArticleDOI
f(T) teleparallel gravity and cosmology
Yi-Fu Cai,Salvatore Capozziello,Mariafelicia De Laurentis,Emmanuel N. Saridakis,Emmanuel N. Saridakis,Emmanuel N. Saridakis +5 more
TL;DR: In this paper, the role of torsion in gravity has been extensively investigated along the main direction of bringing gravity closer to its gauge formulation and incorporating spin in a geometric description.
Journal ArticleDOI
A Critical Review of Classical Bouncing Cosmologies
Diana Battefeld,Patrick Peter +1 more
TL;DR: A comprehensive review of bouncing cosmologies can be found in this article, where the authors provide a pedagogical introduction to these problems and also assess the fitness of different proposals with respect to the data.
Journal ArticleDOI
Bouncing Cosmologies: Progress and Problems
TL;DR: In this paper, the authors review the status of bouncing cosmologies as alternatives to cosmological inflation for providing a description of the very early universe, and a source for the Cosmological perturbations which are observed today.
Journal ArticleDOI
Bouncing Cosmologies: Progress and Problems
TL;DR: In this paper, the authors review the status of bouncing cosmologies as alternatives to cosmological inflation for providing a description of the very early universe, and a source for the Cosmological perturbations which are observed today.
References
More filters
Journal ArticleDOI
First year Wilkinson Microwave Anisotropy Probe (WMAP) observations: Preliminary maps and basic results
Charles L. Bennett,Mark Halpern,Gary Hinshaw,N. Jarosik,Alan J. Kogut,Michele Limon,Michele Limon,S. S. Meyer,Lyman A. Page,David N. Spergel,Gregory S. Tucker,Gregory S. Tucker,Gregory S. Tucker,Edward J. Wollack,Edward L. Wright,Cris W. Barnes,M. R. Greason,Robert S. Hill,Eiichiro Komatsu,M. R. Nolta,N. Odegard,Hiranya V. Peiris,Licia Verde,Janet Weiland +23 more
TL;DR: In this paper, the authors present full sky microwave maps in five frequency bands (23 to 94 GHz) from the WMAP first year sky survey, which are consistent with the 7 in. full-width at half-maximum (FWHM) Cosmic Background Explorer (COBE) maps.
Book
Theory of Cosmological Perturbations
TL;DR: In this paper, the authors present in a manifestly gauge-invariant form the theory of classical linear gravitational perturbations in part I, and a quantum theory of cosmological perturbation in part II.
Journal ArticleDOI
Galileon as a local modification of gravity
TL;DR: In this article, the authors study the connection between self-acceleration and the presence of ghosts for a quite generic class of theories that modify gravity in the infrared, defined as those that at distances shorter than cosmological, reduce to a certain generalization of the Dvali-Gabadadze-Porrati (DGP) effective theory.
Journal ArticleDOI
Ekpyrotic universe: Colliding branes and the origin of the hot big bang
TL;DR: In this article, a cosmological scenario in which the hot big bang universe is produced by the collision of a brane in the bulk space with a bounding orbifold plane, beginning from an otherwise cold, vacuous, static universe was proposed.