A primordial inflationary phase allows one to erase any possible anisotropic expansion thanks to the cosmic no-hair theorem. If there is no global anisotropic stress, then the anisotropic expansion rate tends to decrease. What are the observational consequences of a possible early anisotropic phase? We first review the dynamics of anisotropic universes and report analytic approximations. We then discuss the structure of dynamical equations for perturbations and the statistical properties of observables, as well as the implication of a primordial anisotropy on the quantization of these perturbations during inflation. Finally we review briefly models based on primordial vector field that evade the cosmic no-hair theorem.
Une phase d'inflation primordiale permet d'effacer une possible expansion anisotrope grâce au théorème de calvitie cosmique. S'il n'y a pas de tenseur des contraintes global, alors le taux d'expansion anisotrope tend à décroître. Quelles sont les conséquences observationnelles de cette possible phase anisotrope ? Nous passons d'abord en revue la dynamique des univers anisotropes et donnons des approximations analytiques. Nous discutons ensuite la structure des équations dynamiques régissant l'évolution des perturbations et les propriétés statistiques des observables, ainsi que l'implication d'une phase anisotrope primordiale sur la quantification de ces perturbations pendant l'inflation. Pour terminer, nous examinons brièvement des modèles basés sur des champs vectoriels primordiaux qui permettent de contourner le théorème de calvitie.
Mots-clés : Cosmologie, Inflation, Anisotropie spatiale
Thiago Pereira 1; Cyril Pitrou 2
@article{CRPHYS_2015__16_10_1027_0, author = {Thiago Pereira and Cyril Pitrou}, title = {Isotropization of the universe during inflation}, journal = {Comptes Rendus. Physique}, pages = {1027--1037}, publisher = {Elsevier}, volume = {16}, number = {10}, year = {2015}, doi = {10.1016/j.crhy.2015.09.002}, language = {en}, }
Thiago Pereira; Cyril Pitrou. Isotropization of the universe during inflation. Comptes Rendus. Physique, Cosmic inflation / Inflation cosmique, Volume 16 (2015) no. 10, pp. 1027-1037. doi : 10.1016/j.crhy.2015.09.002. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/j.crhy.2015.09.002/
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