Inflating an Inhomogeneous Universe

Abstract

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 homogeneous dynamics may depend sensitively on the initial configuration. This paper presents an initial survey of the onset of inflation in multifield models, via qualitative lattice-based simulations that do not include local gravitational backreaction. Using hybrid inflation as a test model, our results suggest that small subhorizon inhomogeneities do play a key role in determining whether inflation begins in multifield scenarios. Interestingly, some configurations which do not inflate in the homogeneous limit "succeed" after inhomogeneity is included, while other initial configurations which inflate in the homogeneous limit "fail" when inhomogeneity is added.

15 pages, 8 figures, 1 table; v2: references added; v3: matches published version

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• Inhomogeneous initial conditions for inflation: A wibbly-wobbly timey-wimey path to salvation
• Geodesic completeness and homogeneity condition for cosmic inflation
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• On the initial singularity and extendibility of flat quasi-de Sitter spacetimes
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• Inhomogeneous Initial Data and Small-Field Inflation
• Robustness of inflation to kinetic inhomogeneities
• Introduction to the number of $e$-folds in slow-roll inflation
• Quantum potentiality in Inhomogeneous Cosmology
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• TwInflation
• The Dynamics of Inhomogeneous Dark Energy
• Primordial gravitational waves and perturbations during an inhomogeneous inflation