Evolution of second-order cosmological perturbations and non-Gaussianity

Bartolo, N.; Matarrese, S.; Riotto, Antonio

doi:10.1088/1475-7516/2004/01/003

Cited by 100 publications

(132 citation statements)

References 51 publications

(271 reference statements)

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“…Although we concentrate on the mixed model of the inflaton and the curvaton in this paper, other mixed model may also be worth investigating. In particular, large non-Gaussianity can also be generated in the modulated reheating [62,63,64,27] and preheating scenarios [65,66,67] so that the implications of such a mixed model on the inflationary parameters and non-Gaussianity are of great interest and will be presented elsewhere [68].…”

Section: Summary and Discussionmentioning

confidence: 99%

Non-Gaussianity, Spectral Index and Tensor Modes in Mixed Inflaton and Curvaton Models

Ichikawa¹,

Suyama²,

Takahashi³

et al. 2008

AIP Conference Proceedings

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We study non-Gaussianity, the spectral index of primordial scalar fluctuations and tensor modes in models where fluctuations from the inflaton and the curvaton can both contribute to the present cosmic density fluctuations. Even though simple single-field inflation models generate only tiny non-Gaussianity, if we consider such a mixed scenario, large non-Gaussianity can be produced. Furthermore, we study the inflationary parameters such as the spectral index and the tensor-to-scalar ratio in this kind of models and discuss in what cases models predict the spectral index and tensor modes allowed by the current data while generating large non-Gaussianity, which may have many implications for model-buildings of the inflationary universe.

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Section: Summary and Discussionmentioning

confidence: 99%

Non-Gaussianity, Spectral Index and Tensor Modes in Mixed Inflaton and Curvaton Models

Ichikawa¹,

Suyama²,

Takahashi³

et al. 2008

AIP Conference Proceedings

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“…These have been studied in great detail [14][15][16][17][18][19] and, even though approximate solutions have been found in specific limits [20][21][22][23][24][25][26][27][28][29], they require a numerical treatment. Numerical convergence is now being reached as the latest codes [30][31][32][33] obtain consistent results.…”

Section: Introductionmentioning

confidence: 99%

Impact of polarization on the intrinsic cosmic microwave background bispectrum

et al. 2014

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(2014) Impact of polarization on the intrinsic cosmic microwave background bispectrum. Physical Review D, 90 (10). ISSN 1550-7998 This version is available from Sussex Research Online: http://sro.sussex.ac.uk/57291/ This document is made available in accordance with publisher policies and may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the URL above for details on accessing the published version. Copyright and reuse:Sussex Research Online is a digital repository of the research output of the University.Copyright and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable, the material made available in SRO has been checked for eligibility before being made available.Copies of full text items generally can be reproduced, displayed or performed and given to third parties in any format or medium for personal research or study, educational, or not-for-profit purposes without prior permission or charge, provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way.Impact of polarization on the intrinsic cosmic microwave background bispectrum We compute the cosmic microwave background (CMB) bispectrum induced by the evolution of the primordial density perturbations, including for the first time both temperature and polarization using a second-order Boltzmann code. We show that including polarization can increase the signal-to-noise by a factor 4 with respect to temperature alone. We find the expected signal-to-noise for this intrinsic bispectrum of S=N ¼ 3.8; 2.9; 1.6 and 0.5 for an ideal experiment with an angular resolution of l max ¼ 3000, the proposed CMB surveys PRISM and COrE, and Planck's polarized data, respectively; the bulk of this signal comes from E-mode polarization and from squeezed configurations. We discuss how CMB lensing is expected to reduce these estimates as it suppresses the bispectrum for squeezed configurations and contributes to the noise in the estimator. We find that the presence of the intrinsic bispectrum will bias a measurement of primordial non-Gaussianity of local type by f intr NL ¼ 0.66 for an ideal experiment with l max ¼ 3000. Finally, we verify the robustness of our results by recovering the analytic approximation for the squeezed-limit bispectrum in the general polarized case.

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“…To accomplish this, the second order cosmological perturbation theory is necessary. So, the perturbation theory beyond the linear order has been investigated by many authors [3,4,5,6] and is a topical subject, in particular, to study the non-Gaussianity generated during the inflation [7] and that will be observed in CMB data [8].In this letter, we show the gauge invariant formulation of the general relativistic second order cosmological perturbations on Friedmann-Robertson-Walker (FRW) universe filled with the perfect fluid. This short letter is prepared to show the aspect of the special importance of our companion paper [10], briefly.…”

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confidence: 99%

Gauge-invariant formulation of second-order cosmological perturbations

Nakamura

2006

Phys. Rev. D

109

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Gauge invariant treatments of the second order cosmological perturbation in a four dimensional homogeneous isotropic universe filled with the perfect fluid are completely formulated without any gauge fixing. We derive all components of the Einstein equations in the case where the first order vector and tensor modes are negligible. These equations imply that the tensor and the vector mode of the second order metric perturbations may be generated by the scalar-scalar mode coupling of the linear order perturbations as the result of the non-linear effects of the Einstein equations.PACS numbers: 04.50.+h, 04.62.+v, 98.80.Jk To clarify the relation between scenarios of the early universe and observational data such as the cosmic microwave background (CMB) anisotropies, the general relativistic cosmological linear perturbation theory has been developed to a high degree of sophistication during the last 25 years [1]. Recently, the first order approximation of the early universe from a homogeneous isotropic one is revealed by the observation of the CMB by Wilkinson Microwave Anisotropy Probe (WMAP) [2] and is suggested that fluctuations in the early universe are adiabatic and Gaussian at least in the first order approximation. One of the next theoretical tasks is to clarify the accuracy of these results, for example, through the non-Gaussianity. To accomplish this, the second order cosmological perturbation theory is necessary. So, the perturbation theory beyond the linear order has been investigated by many authors [3,4,5,6] and is a topical subject, in particular, to study the non-Gaussianity generated during the inflation [7] and that will be observed in CMB data [8].In this letter, we show the gauge invariant formulation of the general relativistic second order cosmological perturbations on Friedmann-Robertson-Walker (FRW) universe filled with the perfect fluid. This short letter is prepared to show the aspect of the special importance of our companion paper [10], briefly. The formulation in this paper is one of the applications of the gauge invariant formulation of the second order perturbation theory on a generic background spacetime developed in Refs. [9,10]. We treat all perturbative variables in the gauge invariant manner. We also derive all components of the second order Einstein equations of cosmological perturbations in terms of these gauge invariant variables without any gauge fixing.First, we explain the "gauge" in general relativistic perturbations [4,5,11]. To explain this, we have to explain what we are doing in perturbation theories, at first. In perturbation theories, we treat two spacetimes. One is the physical spacetime M which we will describe by perturbations. In cosmological perturbations, M is an uni- * E-mail address: kouchan@th.nao.ac.jp verse with small inhomogeneities. Another is the background spacetime M 0 which is prepared for perturbative analyses. In cosmological perturbations, M 0 is the FRW universe with the metricwhere γ ij is the metric on a maximally symmetric 3-space with curvat...

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Evolution of second-order cosmological perturbations and non-Gaussianity

Cited by 100 publications

References 51 publications

Non-Gaussianity, Spectral Index and Tensor Modes in Mixed Inflaton and Curvaton Models

Non-Gaussianity, Spectral Index and Tensor Modes in Mixed Inflaton and Curvaton Models

Impact of polarization on the intrinsic cosmic microwave background bispectrum

Gauge-invariant formulation of second-order cosmological perturbations

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