Systematic Distortion in Cosmic Microwave Background Maps

TL;DR

This paper identifies significant systematic deviations from Gaussianity in WMAP CMB maps, highlighting potential calibration issues that could impact precision cosmology.

Contribution

It introduces a method to analyze residual systematic errors in CMB maps, revealing deviations not attributable to early universe processes.

Findings

Detected notable systematic deviation from Gaussianity in WMAP maps

Deviation cannot be explained by early universe processes

Implications for calibration and analysis of CMB data

Abstract

To minimize instrumentally induced systematic errors, cosmic microwave background (CMB) anisotropy experiments measure temperature differences across the sky using paires of horn antennas, temperature map is recovered from temperature differences obtained in sky survey through a map-making procedure. To inspect and calibrate residual systematic errors in recovered temperature maps is important as most previous studies of cosmology are based on these maps. By analyzing pixel-ring couping and latitude dependence of CMB temperatures, we find notable systematic deviation from CMB Gaussianity in released Wilkinson Microwave Anisotropy Probe (WMAP) maps. The detected deviation is hard to explain by any process in the early universe and can not be ignored for a precision cosmology study.