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

Abstract

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-Loeve transformation to take account of the constraints from the temperature data. A polarization map covering at least $\sim 60\%$ of the sky should be able to provide a $3\sigma$ 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.

Accepted for publication in Phys. Rev. D. Minor changes from v1 to match accepted version

References in corpus (12)

• Hemispherical power asymmetry in the three-year Wilkinson Microwave Anisotropy Probe sky maps
• A Hemispherical Power Asymmetry from Inflation
• Power asymmetry in WMAP and Planck temperature sky maps as measured by a local variance estimator
• Superhorizon Perturbations and the Cosmic Microwave Background
• 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
• Broken Isotropy from a Linear Modulation of the Primordial Perturbations
• Power Asymmetries in the Cosmic Microwave Background Temperature and Polarization patterns
• Local variance asymmetries in Planck temperature anisotropy maps
• Physics of the cosmic microwave background anisotropy
• Microwave Background Polarization as a Probe of Large-Angle Correlations