The Nature of Primordial Fluctuations from Anisotropic Inflation

In the model of solid / elastic inflation, inflation is driven by a source that has the field theoretical description of a solid. To allow for prolonged slow roll inflation, the solid needs to be extremely insensitive to the spatial expansion. We point out that, because of this property, the solid is also rather inefficient in erasing anisotropic deformations of the geometry. This allows for a prolonged inflationary anisotropic solution, providing the first example with standard gravity and scalar fields only which evades the conditions of the so called cosmic no-hair conjecture. We compute the curvature perturbations on the anisotropic solution, and the corresponding phenomenological bound on the anisotropy. Finally, we discuss the analogy between this model and the f (φ) F 2 model, which also allows for anisotropic inflation thanks to a suitable coupling between the inflaton φ and a vector field. We remark that the bispectrum of the curvature perturbations in solid inflation is enhanced in the squeezed limit and presents a nontrivial angular dependence, as had previously been found for the f (φ) F 2 model.

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“…Finally, we note that, while the f (φ) F 2 results in a negative g * [62][63][64], in our case both signs of g * are possible.…”

Section: A Computation Of Hintmentioning

confidence: 68%

Anisotropy in solid inflation

Bartolo

Matarrese

Peloso

et al. 2013

J. Cosmol. Astropart. Phys.

107

150

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“…[7,8,9, 10] studied anisotropic inflation with various types of scalar and vector fields, and Refs. [11,12,13,14,15,16,17] discussed relevant perturbation theories. More comprehensive investigations are presented in the review of Ref.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic inflation with general potentials

Shi

Huang

Qiu

2016

Sci. China Phys. Mech. Astron.

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Anomalies in recent observational data indicate that there might be some "anisotropic hair" generated in an inflation period. To obtain general information about the effects of this anisotropic hair to inflation models, we studied anisotropic inflation models that involve one vector and one scalar using several types of potentials. We determined the general relationship between the degree of anisotropy and the fraction of the vector and scalar fields, and concluded that the anisotropies behave independently of the potentials. We also generalized our study to the case of multi-directional anisotropies.

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“…In the following we will use the metric in the form 5) where in the case of an isotropic space-time τ corresponds to conformal time. Transforming these solutions to the time variable τ , the scale factors take the form 6) where…”

Section: Strings In Anisotropic Backgroundsmentioning

confidence: 99%

Effects of anisotropic dynamics on cosmic strings

Kunze¹,

Sakellariadou²

2011

J. Cosmol. Astropart. Phys.

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The dynamics of cosmic strings is considered in anisotropic backgrounds. In particular, the behaviour of infinitely long straight cosmic strings and of cosmic string loops is determined. Small perturbations of a straight cosmic string are calculated. The relevance of these results is discussed with respect to the possible observational imprints of an anisotropic phase on the behaviour of a cosmic string network.

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The Nature of Primordial Fluctuations from Anisotropic Inflation

Cited by 213 publications

References 40 publications

Anisotropy in solid inflation

Anisotropy in solid inflation

Anisotropic inflation with general potentials

Effects of anisotropic dynamics on cosmic strings

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