Pseudo-Dipole Signal Removal from WMAP Data

TL;DR

This paper identifies and removes pseudo-dipole signals caused by systematic errors in WMAP data, revealing that much of the observed quadrupole is artificial and not of cosmological origin.

Contribution

It introduces a uniform modeling and removal method for pseudo-dipole signals in WMAP data, improving the accuracy of CMB anisotropy measurements.

Findings

Most of the WMAP CMB quadrupole is artificial.

Pseudo-dipole signals can be effectively modeled and removed.

Systematic errors significantly affect CMB anisotropy measurements.

Abstract

It is discovered in our previous work that different observational systematics, e.g., errors of antenna pointing directions, asynchronous between the attitude and science data, can generate pseudo-dipole signal in full-sky maps of the cosmic microwave background (CMB) anisotropy published by The Wilkinson Microwave Anisotropy Probe (WMAP) team. Now the antenna sidelobe response to the Doppler signal is found to be able to produce similar effect as well. In this work, independent to the sources, we uniformly model the pseudo-dipole signal and remove it from published WMAP7 CMB maps by model fitting. The result demonstrates that most of the released WMAP CMB quadrupole is artificial.