Gravitational wave spectrum induced by primordial scalar perturbations

Baumann, Daniel; Steinhardt, Paul J.; Takahashi, Keitaro; Ichiki, Kiyotomo

doi:10.1103/physrevd.76.084019

Cited by 686 publications

(910 citation statements)

References 37 publications

Supporting

Mentioning

890

Contrasting

Order By: Relevance

“…Furthermore, one can generalize our method to study the evolution of perturbations in a Universe filled with several coupled fluids, by introducing a correspondent number of derivatively coupled scalar fields in the action, with possible couplings between them. As a future study, this method could be used to study the generation of gravitational waves from second order perturbations during radiation and matter dominated era [17,18].…”

Section: Discussionmentioning

confidence: 99%

Action approach to cosmological perturbations: the second-order metric in matter dominance

Boubekeur

Creminelli

Noreña

et al. 2008

J. Cosmol. Astropart. Phys.

117

View full text Add to dashboard Cite

We study nonlinear cosmological perturbations during the post-inflationary evolution, using the equivalence between a perfect barotropic fluid and a derivatively coupled scalar field with Lagrangian [−(∂φ) 2 ] (1+w)/2w . Since this Lagrangian is just a special case of k-inflation, this approach is analogous to the one employed in the study of non-Gaussianities from inflation. We use this method to derive the second order metric during matter dominance in the comoving gauge directly as function of the primordial inflationary perturbation ζ. Going to Poisson gauge, we recover the metric previously derived in the literature.

show abstract

Section: Discussionmentioning

confidence: 99%

Action approach to cosmological perturbations: the second-order metric in matter dominance

Boubekeur

Creminelli

Noreña

et al. 2008

J. Cosmol. Astropart. Phys.

117

View full text Add to dashboard Cite

show abstract

“…16; thus, the cyclic model and any other one using an ekpyrotic phase would be ruled out if no other source for primordial gravitational waves at CMBR scales were present. If future experiments refute the BICEP2 claims and reveal no nearly scale-invariant, first order tensor spectrum, but a measurable scalar induced, second order tensor spectrum instead, inflation would be in trouble and alternative models, such as the ekpyrotic/cyclic ones would be favored [421]. For a comparison of the spectrum of scalar induced tensors with gravitational waves generated during inflation and current and future experiments see Fig.…”

Section: Matching Conditionsmentioning

confidence: 99%

“…In this case, the dominant source for gravitational waves are second order effects, whereby h ij is sourced by scalar fluctuations [421].…”

Section: Matching Conditionsmentioning

confidence: 99%

See 1 more Smart Citation

A critical review of classical bouncing cosmologies

2015

View full text Add to dashboard Cite

Given the proliferation of bouncing models in recent years, we gather and critically assess these proposals in a comprehensive review. The PLANCK data shows an unmistakably red, quasi scaleinvariant, purely adiabatic primordial power spectrum and no primary non-Gaussianities. While these observations are consistent with inflationary predictions, bouncing cosmologies aspire to provide an alternative framework to explain them. Such models face many problems, both of the purely theoretical kind, such as the necessity of violating the NEC and instabilities, and at the cosmological application level, as exemplified by the possible presence of shear. We provide a pedagogical introduction to these problems and also assess the fitness of different proposals with respect to the data. For example, many models predict a slightly blue spectrum and must be fine-tuned to generate a red spectral index; as a side effect, large non-Gaussianities often result.We highlight several promising attempts to violate the NEC without introducing dangerous instabilities at the classical and/or quantum level. If primordial gravitational waves are observed, certain bouncing cosmologies, such as the cyclic scenario, are in trouble, while others remain valid. We conclude that, while most bouncing cosmologies are far from providing an alternative to the inflationary paradigm, a handful of interesting proposals have surfaced, which warrant further research. The constraints and lessons learned as laid out in this review might guide future research.

show abstract

“…Refs [26,27,28] for analysis of vector and tensor modes generation at second order). In Newtonian gauge, we can expand the metric as…”

Section: B Perturbation Variablesmentioning

confidence: 99%

Cosmic microwave background bispectrum on small angular scales

2008

View full text Add to dashboard Cite

This article investigates the non-linear evolution of cosmological perturbations on sub-Hubble scales in order to evaluate the unavoidable deviations from Gaussianity that arise from the nonlinear dynamics. It shows that the dominant contribution to modes coupling in the cosmic microwave background temperature anisotropies on small angular scales is driven by the sub-Hubble nonlinear evolution of the dark matter component. The perturbation equations, involving in particular the first moments of the Boltzmann equation for photons, are integrated up to second order in perturbations. An analytical analysis of the solutions gives a physical understanding of the result as well as an estimation of its order of magnitude. This allows to quantify the expected deviation from Gaussianity of the cosmic microwave background temperature anisotropy and, in particular, to compute its bispectrum on small angular scales. Restricting to equilateral configurations, we show that the non-linear evolution accounts for a contribution that would be equivalent to a constant primordial non-Gaussianity of order f NL ∼ 25 on scales ranging approximately from ℓ ∼ 1000 to ℓ ∼ 3000.

show abstract

Gravitational wave spectrum induced by primordial scalar perturbations

Cited by 686 publications

References 37 publications

Action approach to cosmological perturbations: the second-order metric in matter dominance

Action approach to cosmological perturbations: the second-order metric in matter dominance

A critical review of classical bouncing cosmologies

Cosmic microwave background bispectrum on small angular scales

Contact Info

Product

Resources

About