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Related papers: Initial Conditions of Inflation in a Bianchi I Uni…

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We investigate whether inflation requires finely tuned initial conditions in order to explain the degree of flatness and homogeneity observed in the Universe. We achieve this by using the Eisenhart lift, which can be used to write any…

General Relativity and Quantum Cosmology · Physics 2019-05-24 Kieran Finn , Sotirios Karamitsos

This article investigates the predictions of an inflationary phase starting from a homogeneous and anisotropic universe of the Bianchi I type. After discussing the evolution of the background spacetime, focusing on the number of e-folds and…

Astrophysics · Physics 2009-06-23 Cyril Pitrou , Thiago S. Pereira , Jean-Philippe Uzan

We extend the standard theory of cosmological perturbations to homogeneous but anisotropic universes. We present an exhaustive computation for the case of a Bianchi I model, with a residual isotropy between two spatial dimensions, which is…

Astrophysics · Physics 2008-11-26 A. E. Gumrukcuoglu , Carlo R. Contaldi , Marco Peloso

We investigate the $\phi^2$ inflationary model in the Bianchi-I spacetime using effective spacetime description of loop quantum cosmology to understand the issues of the resolution of initial singularity, isotropization, effect of…

General Relativity and Quantum Cosmology · Physics 2013-07-11 Brajesh Gupt , Parampreet Singh

Using numerical solutions of the full Einstein field equations coupled to a scalar inflaton field in 3+1 dimensions, we study the conditions under which a universe that is initially expanding, highly inhomogeneous and dominated by gradient…

High Energy Physics - Theory · Physics 2016-09-07 William E. East , Matthew Kleban , Andrei Linde , Leonardo Senatore

While cosmological inflation can erase primordial inhomogeneities, it is possible that inflation may not begin in a significantly inhomogeneous universe. This issue is particularly pressing in multifield scenarios, where even the…

Cosmology and Nongalactic Astrophysics · Physics 2014-08-25 Richard Easther , Layne C. Price , Javier Rasero

We investigate the circumstances under which cosmic inflation can arise from very inhomogeneous initial conditions using numerical relativity simulations. Previous studies have not considered cases with non-zero momentum density due to…

General Relativity and Quantum Cosmology · Physics 2023-12-15 Maxence Corman , William E. East

The behaviour of a non-canonical scalar field within an anisotropic Bianchi type I, spatially homogeneous, Universe in the framework of the intermediate inflation will be studied. It will be examined on the condition that both the…

General Physics · Physics 2019-08-19 Mahdeyeh Naderi , Ali Aghamohammadi , Abdollah Refaei , Haidar Sheikhahmadi

Recently an inflationary model with a vector field coupled to the inflaton was proposed and the phenomenology studied for the Bianchi type I spacetime. It was found that the model demonstrates a counter-example to the cosmic no-hair theorem…

General Relativity and Quantum Cosmology · Physics 2011-12-22 Sigbjørn Hervik , David F. Mota , Mikjel Thorsrud

Using a long wavelength iteration scheme to solve Einstein's equations near the Big-Bang singularity of a universe driven by a massive scalar field, we find how big initial quasi-isotropic inhomogeneities can be before they can prevent…

General Relativity and Quantum Cosmology · Physics 2009-10-22 Nathalie Deruelle , Dalia S. Goldwirth

The inflationary scenario, which states that the early universe underwent a brief but dramatic period of accelerated spatial expansion, has become the current paradigm of early universe cosmology. Although inflationary cosmology has its…

General Relativity and Quantum Cosmology · Physics 2024-06-04 Eric Ling , Annachiara Piubello

We examine the behavior of an anisotropic brane-world in the presence of inflationary scalar fields. We show that, contrary to naive expectations, a large anisotropy does not adversely affect inflation. On the contrary, a large initial…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Roy Maartens , Varun Sahni , Tarun Deep Saini

We analyze the onset of inflation for a simple single-field model when the system begins with significant inhomogeneities on length-scales shorter than the initial Hubble radius. We incorporate certain nonlinear interactions among the…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-17 Jolyon K. Bloomfield , Patrick Fitzpatrick , Kiriakos Hilbert , David I. Kaiser

Cosmic inflation is arguably the most favoured paradigm of the very early Universe. It postulates an early phase of fast, nearly exponential, and accelerated expansion. Inflationary models are capable of explaining the overall flatness and…

Cosmology and Nongalactic Astrophysics · Physics 2022-11-08 Cristian Joana

The possibility of the resilience of the beginning of inflation under unfavorable conditions is examined by considering the initial state of the inflaton field to be in the form of a relativistic gas with some of its properties in close…

High Energy Physics - Theory · Physics 2023-04-05 Lasha Berezhiani , Mark Trodden

The influence of Inflation on initial (i.e. at Planck's epoch) large anisotropy of the Universe is studied, considering a more general metric than the isotropic one: the locally rotationally symmetric (L.R.S.) Bianchi IX metric. We find,…

General Relativity and Quantum Cosmology · Physics 2014-11-17 R. Bergamini , P. Sedici , P. Verrocchio

I give a brief review of the status of research on the nature of initial conditions required to obtain a period of cosmological inflation. It is shown that there is good evidence that in the case of large field models, the inflationary…

High Energy Physics - Theory · Physics 2017-02-08 Robert Brandenberger

In this work we study models of anisotropic inflation with the generalized non-vacuum initial states for the inflaton field and the gauge field. The effects of non Bunch-Davies initial condition on the anisotropic power spectrum and…

High Energy Physics - Theory · Physics 2014-07-09 Razieh Emami , Hassan Firouzjahi , Moslem Zarei

We present a detailed discussion of the inflationary scenario in the context of inhomogeneous cosmologies. After a review of the fundamental features characterizing the inflationary model, as referred to a homogeneous and isotropic…

General Relativity and Quantum Cosmology · Physics 2010-11-11 Giovanni Imponente , Giovanni Montani

We discuss the issue of setting appropriate initial conditions for inflation. Specifically, we consider natural inflation model and discuss the fine tuning required for setting almost homogeneous initial conditions over a region of order…

High Energy Physics - Theory · Physics 2021-05-17 Partha Bagchi , Arpan Das , Shreyansh S. Dave , Srikumar Sengupta , Ajit M. Srivastava
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