Related papers: The hemispherical asymmetry from a scale-dependent…
Observations of the microwave background fluctuations suggest a scale-dependent amplitude asymmetry of roughly 2.5 sigma significance. Inflationary explanations for this 'anomaly' require non-Gaussian fluctuations which couple observable…
We investigate if the hemispherical asymmetry in the CMB is produced from "asymmetric" excited initial condition. We show that in the limit where the deviations from the Bunch-Davies vacuum is large and the scale of new physics is maximally…
We demonstrate that a topological defect can explain the hemispherical power asymmetry of the CMB. The first point is that a defect configuration, which already exists prior to inflation, can source asymmetry of the CMB. The second point is…
We consider a general initial state for inflation as the mechanism for generating scale-dependent hemispherical asymmetry. An observable scale-dependent non-Gaussianity is generated that leads to observable hemispherical asymmetry from the…
We explore a plausible mechanism that the hemispherical power asymmetry in the CMB is produced by the spatial variation of the primordial sound speed parameter. We suggest that in a generalized approach of the $\delta N$ formalism the local…
The observed hemispherical asymmetry in CMB map can be explained by modulation from a long wavelength super horizon mode which non-linearly couples to the CMB modes. We address the criticism in [1] about the role of non-Gaussianities in…
The hemispherical power asymmetry observed by Planck and WMAP can be interpreted as due to a spatially-varying and scale-dependent component of the adiabatic power spectrum. We derive general constraints on the magnitude and…
The CMB bispectrum generated by second-order effects at recombination can be calculated analytically when one of the three modes has a wavelength much longer than the other two and is outside the horizon at recombination. This was pointed…
We study statistical anisotropies generated in the observed two-point function of the cosmic microwave background (CMB) fluctuations if the primordial statistics are non-Gaussian. Focusing on the dipole modulations of the anisotropies, we…
We reconsider the observed CMB dipolar asymmetry in the context of open inflation, where a supercurvature mode might survive the bubble nucleation. If such a supercurvature mode modulates the amplitude of the curvature power spectrum, it…
We investigate the hemispherical power asymmetry observed in the CMBR by attributing it to an early inhomogeneous phase of cosmic expansion. Unlike the conventional assumption of a perfectly isotropic and homogeneous pre-inflationary…
In this paper we provide a consistency relation between the amplitude of the hemispherical bipolar asymmetry, $A$, and the amplitude of the primordial non-Gaussianity in the squeezed limit, $f_{NL}$, as $|A| \lesssim 10^{-1} f_{NL}$. We…
Statistical isotropy is often assumed in cosmology and should be tested rigorously against observational data. We construct simple quadratic estimators to reconstruct asymmetry in the primordial power spectrum from CMB temperature and…
Measurements of CMB temperature fluctuations by the Wilkinson Microwave Anisotropy Probe (WMAP) indicate that the fluctuation amplitude in one half of the sky differs from the amplitude in the other half. We show that such an asymmetry…
We analyze an inflationary model in which part of the power in density perturbations arises due to particle production. The amount of particle production is modulated by an auxiliary field. Given an initial gradient for the auxiliary field,…
We propose a new model for the hemispherical power asymmetry of the CMB based on modulated reheating. Non-Gaussianity from modulated reheating can be small enough to satisfy the bound from Planck if the dominant modulation of the inflaton…
Lensing of the CMB generates a significant bispectrum, which should be detected by the Planck satellite at the 5-sigma level and is potentially a non-negligible source of bias for f_NL estimators of local non-Gaussianity. We extend current…
We study the asymmetric primordial fluctuations in a model of inflation in which translational invariance is broken by a domain wall. We calculate the corrections to the power spectrum of curvature perturbations; they are anisotropic and…
Measurement of Cosmic Microwave Background (CMB) temperature by Planck has resulted in extremely tight constraints on the $\Lambda$CDM model. However the data indicates a evidence of dipole modulated temperature fluctuations at large…
Erickcek, Kamionkowski and Carroll proposed in 2008 that the dipole modulation of the CMB could be due to a very large scale perturbation of the field $\phi$ causing the primordial curvature perturbation. We repeat their calculation using…