Relic Gravitational Waves and CMB Polarization in the Accelerating Universe

Zhang, Y.; Zhao, Wen; Xia, Tianyang; Er, Xinzhong; Miao, H.

doi:10.1142/s0218271808012735

Cited by 16 publications

(7 citation statements)

References 51 publications

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“…However, as pointed out in [32,89], this may not be the case when the collapse dynamics is also taken into account. We now calculate the CSL contribution to the evolution ofR 2 during the radiation-dominated era, which lasts from time η e to η r ¼ 3 × 10 60 M −1 P which is estimated by using the fact that aðη r Þ=aðη e Þ ≈ 3 × 10 26 [90]. Notice that, as a first approximation, we are not including effects due to the reheating stage [90], and directly consider the radiation-dominated era as following the inflationary one.…”

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confidence: 99%

Impact of Dynamical Collapse Models on Inflationary Cosmology

et al. 2021

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Inflation solves several cosmological problems at the classical and quantum level, with a strong agreement between the theoretical predictions of well-motivated inflationary models and observations. In this Letter, we study the corrections induced by dynamical collapse models, which phenomenologically solve the quantum measurement problem, to the power spectrum of the comoving curvature perturbation during inflation and the radiation-dominated era. We find that the corrections are strongly negligible for the reference values of the collapse parameters.

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confidence: 99%

Impact of Dynamical Collapse Models on Inflationary Cosmology

et al. 2021

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“…(5) has been solved by perturbations, yielding the full analytic solution h k (η), from the inflation up to the present accelerating stage [14,19], and it has been found that the relativistic freestreaming gas causes a damping of h k by ∼ 20% in the frequency range ν ≃ (10 −16 , 10 −10 )Hz. The RGWs can generate the CMB temperature and polarization anisotropies power spectra C XX ′ ℓ (XX ′ = T T, T E, EE, BB), by the Sachs-Wolfe effect [13,14,24,25,26,27,28,29,30,31,32]. As shown in Ref [14], the mode functions h k (η d ) andḣ k (η d ) at the photon decoupling time η d , i.e.…”

Section: Effects Of Free-streaming Gas On Rgws and Cmb Polarizationsmentioning

confidence: 99%

New method to constrain the relativistic free-streaming gas in the Universe

Zhao¹,

Zhang²,

Xia³

2009

Physics Letters B

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We discuss a method to constrain the fraction density f of the relativistic gas in the radiationdominant stage, by their impacts on a relic gravitational waves and the cosmic microwave background (CMB) B-polarization power spectrum. We find that the uncertainty of f strongly depends on the noise power spectra of the CMB experiments and the amplitude of the gravitational waves. Taking into account of the CMBPol instrumental noises, an uncertainty ∆f = 0.046 is obtained for the model with tensor-to-scalar ratio r = 0.1. For an ideal experiment with only the reduced cosmic lensing as the contamination of B-polarization, ∆f = 0.008 is obtained for the model with r = 0.1. So the precise observation of the CMB B-polarization provides a great opportunity to study the relativistic components in the early Universe.

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“…There are several works in the field that extracted an analytical expression for the C XX , in a flat universe such as Refs. [5,6,7,8,9,10,11] where all analytical spectra have been extracted by considering the tensor perturbation as a source. Ref.…”

Section: Introductionmentioning

confidence: 99%

An analytical approach to the CMB polarization in a spatially closed background

Niazy

Abbassi

2018

Physics of the Dark Universe

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The scalar mode polarization of the cosmic microwave background is derived in a spatially closed universe from the Boltzmann equation using the line of sight integral method. The EE and TE multipole coefficients have been extracted analytically by considering some tolerable approximations such as considering the evolution of perturbation hydrodynamically and sudden transition from opacity to transparency at the time of last scattering. As the major advantage of analytic expressions, C S EE, and C S T E, explicitly show the dependencies on baryon density Ω B , matter density Ω M , curvature Ω K , primordial spectral index n s , primordial power spectrum amplitude A s , Optical depth τ reion , recombination width σ t and recombination time t L . Using a realistic set of cosmological parameters taken from a fit to data from Planck, the closed universe EE and TE power spectrums in the scalar mode are compared with numerical results from the CAMB code and also latest observational data. The analytic results agree with the numerical ones on the big and moderate scales. The peak positions are in good agreement with the numerical result on these scales while the peak heights agree with that to within 20% due to the approximations have been considered for these derivations. Also, several interesting properties of CMB polarization are revealed by the analytic spectra.

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Relic Gravitational Waves and CMB Polarization in the Accelerating Universe

Cited by 16 publications

References 51 publications

Impact of Dynamical Collapse Models on Inflationary Cosmology

Impact of Dynamical Collapse Models on Inflationary Cosmology

New method to constrain the relativistic free-streaming gas in the Universe

An analytical approach to the CMB polarization in a spatially closed background

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