Implications of the cosmic microwave background power asymmetry for the early universe

Byrnes, Christian T.; Regan, Donough; Seery, David; Tarrant, Ewan R. M.

doi:10.1103/physrevd.93.123003

Cited by 15 publications

(16 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…including larger modes and measuring the scale dependence of f NL from bispectrum measurements with the latest data) is necessary to see how useful the inclusion of A 0 , in addition to the power asymmetry amplitude, proves to be in the actual CMB data. In addition, we have chosen a simple model that may capture the features seen in the data but that may not be easily achievable from an inflationary point of view [81].…”

Section: Discussionmentioning

confidence: 99%

Large-scale anomalies in the cosmic microwave background as signatures of non-Gaussianity

2016

View full text Add to dashboard Cite

We derive a general expression for the probability of observing deviations from statistical isotropy in the cosmic microwave background (CMB) if the primordial fluctuations are non-Gaussian and extend to superhorizon scales. The primary motivation is to properly characterize the monopole and dipole modulations of the primordial power spectrum that are generated by the coupling between superhorizon and subhorizon perturbations. Unlike previous proposals for generating the hemispherical power asymmetry, we do not assume that the power asymmetry results from a single large superhorizon mode. Instead, we extrapolate the observed power spectrum to superhorizon scales and compute the power asymmetry that would result from a specific realization of non-Gaussian perturbations on scales larger than the observable universe. Our study encompasses many of the scenarios that have been put forward as possible explanations for the CMB hemispherical power asymmetry. We confirm our analytic predictions for the probability of a given power asymmetry by comparing them to numerical realizations of CMB maps. We find that non-local models of nonGaussianity and scale-dependent local non-Gaussianity produce scale-dependent modulations of the power spectrum, thereby potentially producing both a monopolar and a dipolar power modulation on large scales. We then provide simple examples of finding the posterior distributions for the parameters of the bispectrum from the observed monopole and dipole modulations.

show abstract

Section: Discussionmentioning

confidence: 99%

Large-scale anomalies in the cosmic microwave background as signatures of non-Gaussianity

2016

View full text Add to dashboard Cite

show abstract

“…In this paper, we go further by comparing this hypothesis with an alternative in which statistical isotropy is broken. The most straightforward candidates for the new-physics hypothesis involve modulating the the primordial perturbations with a long-wavelength mode [28][29][30][31][32][33][34], although there are other possibilities as well [35]. Such a modulation can be produced in inflationary scenarios with a curvaton field, among other ways.…”

Section: Introductionmentioning

confidence: 99%

Testing cosmological models with large-scale power modulation using microwave background polarization observations

2016

View full text Add to dashboard Cite

We examine the degree to which observations of large-scale cosmic microwave background (CMB) polarization can shed light on the puzzling large-scale power modulation in maps of CMB anisotropy. We consider a phenomenological model in which the observed anomaly is caused by modulation of large-scale primordial curvature perturbations and calculate Fisher information and error forecasts for future polarization data, constrained by the existing CMB anisotropy data. Because a significant fraction of the available information is contained in correlations with the anomalous temperature data, it is essential to account for these constraints. We also present a systematic approach to finding a set of normal modes that maximize the available information, generalizing the well-known Karhunen-Loève transformation to take account of the constraints from the temperature data. A polarization map covering at least ∼60% of the sky should be able to provide a 3σ detection of modulation at the level favored by the temperature data. A significant fraction of the information in such a data set is contained in the single mode that optimally encapsulates the signal due to temperature-polarization correlation.

show abstract

“…To be consistent with their results, we adopt the best-fitting central value of cosmological parameters released by the Planck 2013 data and use the formula of angular correlation coefficients (28) and (29) to plot numerical results for the anisotropic part of C ll . One can find from Eqs.…”

Section: Cmb Power Spectra With Dipolar Modulationmentioning

confidence: 99%

“…One can find from Eqs. (28,29) that the anisotropic part of C ll depends on m, and the T E and E T correlation coefficients are different.…”

Section: Cmb Power Spectra With Dipolar Modulationmentioning

confidence: 99%

See 1 more Smart Citation

Finslerian dipolar modulation of the CMB power spectra at scales $$2<l<600$$ 2 < l < 600

Lin

2017

Eur. Phys. J. C

View full text Add to dashboard Cite

A common explanation for the CMB power asymmetry is to introduce a dipolar modulation at the stage of inflation, where the primordial power spectrum is spatially varying. If the universe in the stage of inflation is Finslerian, and if the Finsler spacetime is non-reversible under parity flip, x → −x, then a three dimensional spectrum which is a function of wave vector and direction is valid. In this paper, a three dimensional primordial power spectrum with preferred direction is derived in the framework of Finsler spacetime. It is found that the amplitude of dipolar modulation is related to the Finslerian parameter, which in turn is a function of wave vector. The angular correlation coefficients are presented, and the numerical results for the anisotropic correlation coefficients over the multipole range 2 < l < 600 are given.

show abstract

Implications of the cosmic microwave background power asymmetry for the early universe

Cited by 15 publications

References 35 publications

Large-scale anomalies in the cosmic microwave background as signatures of non-Gaussianity

Large-scale anomalies in the cosmic microwave background as signatures of non-Gaussianity

Testing cosmological models with large-scale power modulation using microwave background polarization observations

Finslerian dipolar modulation of the CMB power spectra at scales $$2<l<600$$ 2 < l < 600

Contact Info

Product

Resources

About