Testing physical models for dipolar asymmetry with CMB polarization

Abstract

The cosmic microwave background (CMB) temperature anisotropies exhibit a large-scale dipolar power asymmetry. To determine whether this is due to a real, physical modulation or is simply a large statistical fluctuation requires the measurement of new modes. Here we forecast how well CMB polarization data from \Planck\ and future experiments will be able to confirm or constrain physical models for modulation. Fitting several such models to the \Planck\ temperature data allows us to provide predictions for polarization asymmetry. While for some models and parameters \Planck\ polarization will decrease error bars on the modulation amplitude by only a small percentage, we show, importantly, that cosmic-variance-limited (and in some cases even \Planck) polarization data can decrease the errors by considerably better than the expectation of $\sqrt{2}$ based on simple $\ell$-space arguments. We project that if the primordial fluctuations are truly modulated (with parameters as indicated by \Planck\ temperature data) then \Planck\ will be able to make a 2$\sigma$ detection of the modulation model with 20--75\% probability, increasing to 45--99\% when cosmic-variance-limited polarization is considered. We stress that these results are quite model dependent. Cosmic variance in temperature is important: combining statistically isotropic polarization with temperature data will spuriously increase the significance of the temperature signal with 30\% probability for \Planck.

18 pages, 11 figures, 2 tables. Version updated to match PRD version

References in corpus (27)

• A Joint Analysis of BICEP2/Keck Array and Planck Data
• BICEP2 / Keck Array VI: Improved Constraints On Cosmology and Foregrounds When Adding 95 GHz Data From Keck Array
• Planck 2015 results. XVI. Isotropy and statistics of the CMB
• Planck 2015 results. IX. Diffuse component separation: CMB maps
• Planck 2015 results. VIII. High Frequency Instrument data processing: Calibration and maps
• Dipoles in the Sky
• Constraints on cosmic hemispherical power anomalies from quasars
• A Scale-Dependent Power Asymmetry from Isocurvature Perturbations
• Testable polarization predictions for models of CMB isotropy anomalies
• Testing Global Isotropy of Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Data: Temperature Analysis
• On the significance of power asymmetries in Planck CMB data at all scales
• Microwave Background Correlations from Dipole Anisotropy Modulation
• Dipolar modulation in number counts of WISE-2MASS sources
• Power Asymmetries in the Cosmic Microwave Background Temperature and Polarization patterns
• Polypolar spherical harmonic decomposition of galaxy correlators in redshift space: Toward testing cosmic rotational symmetry
• Violation of statistical isotropy and homogeneity in the 21-cm power spectrum
• The information content of cosmic microwave background anisotropies
• Expected dipole asymmetry in CMB polarization
• Dipole Modulation of Cosmic Microwave Background Temperature and Polarization
• Testing physical models for dipolar asymmetry: from temperature to k space to lensing
• Imprint of Inhomogeneous and Anisotropic Primordial Power Spectrum on CMB Polarization
• Lensing as a Probe of Early Universe: from CMB to Galaxies
• Linking the BICEP2 result and the hemispherical power asymmetry through spatial variation of $r$
• Scalar-tensor correlations and large-scale power suppression
• Fingerprints of Anomalous Primordial Universe on the Abundance of Large Scale Structures
• A forecast for the detection of the power asymmetry from galaxy surveys
• Testing cosmological models with large-scale power modulation using microwave background polarization observations

Cited by in corpus (14)

• Planck 2018 results. X. Constraints on inflation
• Planck 2018 results. VII. Isotropy and Statistics of the CMB
• Covariance of CMB anomalies
• Towards testing CMB anomalies using the kinetic and polarized Sunyaev Zel'dovich effects
• A Global ILC Approach in Pixel Space over Large Angular Scales of the Sky using CMB Covariance Matrix
• Joint Bayesian analysis of large angular scale CMB temperature anomalies
• Isotropic non-Gaussian $g_{\mathrm{NL}}$-like toy models that reproduce the cosmic microwave background anomalies
• A Pixel Space Method for Testing Dipole Modulation in the CMB Polarization
• A forecast for the detection of the power asymmetry from galaxy surveys
• Statistical anisotropies in temperature and polarization fluctuations from a scale-dependent trispectrum
• Closing in on the large-scale CMB power asymmetry
• CMB Polarization by the Asymmetric Template of Scalar Perturbations
• A comprehensive study of Modulation effects on CMB Polarization
• Quarkonia as probes of the QGP and the initial stages of the heavy-ion collisions with ALICE