Cosmological perturbations from vector inflation

Golovnev, Alexey; Vanchurin, Vitaly

doi:10.1103/physrevd.79.103524

Cited by 59 publications

(66 citation statements)

References 16 publications

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“…One could support isotropic expansion long enough with sufficiently finely tuned initial conditions as in the vector field inflation model of [5], or invoke a regiment of vector fields in such a way that on average they do not manifest any preferred direction, as in the model put forward by [6,7], see also [8][9][10][11][12]. With non-minimal coupling to gravity or non-standard vector fields, such as in three-form inflation and dark energy models, a time-like (and thus isotropic) field would include non-trivial (yet observationally appropriate) cosmologies [13][14][15][16][17][18][19][20][21][22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Doubly-boosted vector cosmologies from disformal metrics

Koivisto

Urban

2015

Phys. Scr.

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A systematic dynamical system approach is applied to study the cosmology of anisotropic Bianchi I universes in which a vector field is assumed to operate on a disformal frame. This study yields a number of new fixed points, among which anisotropic scaling solutions. Within the simplifying assumption of (nearly) constant-slope potentials these are either not stable attractors, do not describe accelerating expansion or else they feature too large anisotropies to be compatible with observations. Nonetheless, some solutions do have an appeal for cosmological applications in that isotropy is retained due to rapid oscillations of the vector field.

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Section: Introductionmentioning

confidence: 99%

Doubly-boosted vector cosmologies from disformal metrics

Koivisto

Urban

2015

Phys. Scr.

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“…For example, inflationary perturbations induced by vector fields [55][56][57][58]. Note however that inflationary models with vector fields usually suffer from instabilities due to the existence of ghosts.…”

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confidence: 99%

Searching for a cosmological preferred axis: Union2 data analysis and comparison with other probes

Antoniou

Perivolaropoulos

2010

J. Cosmol. Astropart. Phys.

153

227

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We review, compare and extend recent studies searching for evidence for a preferred cosmological axis. We start from the Union2 SnIa dataset and use the hemisphere comparison method to search for a preferred axis in the data. We find that the hemisphere of maximum accelerating expansion rate is in the direction (l, b) = (309•+11• −10 • ) (Ω0m = 0.19) while the hemisphere of minimum acceleration is in the opposite direction (l, b) = (129The level of anisotropy is described by the normalized difference of the best fit values of Ω0m between the two hemispheres in the context of ΛCDM fits. We find a maximum anisotropy level in the Union2 data of= 0.43 ± 0.06. Such a level does not necessarily correspond to statistically significant anisotropy because it is reproduced by about 30% of simulated isotropic data mimicking the best fit Union2 dataset. However, when combined with the axes directions of other cosmological observations (bulk velocity flow axis, three axes of CMB low multipole moments and quasar optical polarization alignment axis), the statistical evidence for a cosmological anisotropy increases dramatically. We estimate the probability that the above independent six axes directions would be so close in the sky to be less than 1%. Thus either the relative coincidence of these six axes is a very large statistical fluctuation or there is an underlying physical or systematic reason that leads to their correlation.

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“…This has been calculated in several models, such as multifield slow-roll inflation [26][27][28][29], in the curvaton mechanism [30], in theories with non-canonical kinetic terms both in single field [31][32][33][34] and in the multifield case [36,37]. 1 We consider here another class of models, specifically those including primordial vector fields [13,[41][42][43][44][45][46][47][48][49]. The interest in these models finds its motivations, besides in the search for a strong non-Gaussian signature, also in the study of statistical anisotropy.…”

Section: Jcap11(2009)028mentioning

confidence: 99%

Anisotropic trispectrum of curvature perturbations induced by primordial non-Abelian vector fields

Bartolo¹,

Dimastrogiovanni²,

Matarrese³

et al. 2009

J. Cosmol. Astropart. Phys.

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Motivated by the interest in models of the early universe where statistical isotropy is broken and can be revealed in cosmological observations, we consider an SU (2) theory of gauge interactions in a single scalar field inflationary scenario. We calculate the trispectrum of curvature perturbations, as a natural follow up to a previous paper of ours, where we studied the bispectrum in the same kind of models. The choice of a non-Abelian set-up turns out to be very convenient: on one hand, gauge boson self-interactions can be very interesting being responsible for extra non-trivial terms (naturally absent in the Abelian case) appearing in the cosmological correlation functions; on the other hand, its results can be easily reduced to the U (1) case. As expected from the presence of the vector bosons, preferred spatial directions arise and the trispectrum reveals anisotropic signatures. We evaluate its amplitude τ N L , which receives contributions both from scalar and vector fields, and verify that, in a large subset of its parameter space, the latter contributions can be larger than the former. We carry out a shape analysis of the trispectrum; in particular we discuss, with some examples, how the anisotropy parameters appearing in the analytic expression of the trispectrum can modulate its profile and we show that the amplitude of the anisotropic part of the trispectrum can be of the same order of magnitude as the isotropic part.

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Cosmological perturbations from vector inflation

Cited by 59 publications

References 16 publications

Doubly-boosted vector cosmologies from disformal metrics

Doubly-boosted vector cosmologies from disformal metrics

Searching for a cosmological preferred axis: Union2 data analysis and comparison with other probes

Anisotropic trispectrum of curvature perturbations induced by primordial non-Abelian vector fields

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