Missing completely of the CMB quadrupole in WMAP data

• Published in: Chinese science bulletin Vol. 58; no. 11; pp. 1243 - 1249
• Main Authors: Liu, Hao, Li, TiPei
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer-Verlag 01.04.2013; SP Science China Press
• Subjects: Chemistry/Food Science; Computer programs; computer software; Contamination; Cosmic microwave background; Dipoles; Earth Sciences; Engineering; Humanities and Social Sciences; Life Sciences; microwave radiometers; multidisciplinary; Physics; Quadrupoles; Science; Science (multidisciplinary); Software; temperature; WMAP; 原始数据; 四级; 地图制作; 威尔金森微波各向异性探测器; 宇宙微波背景辐射; 微波辐射计; 标准宇宙模型; cosmic microwave background; data analysis; cosmology
• ISSN: 1001-6538; 1861-9541; 1861-9541
• DOI: 10.1007/s11434-013-5735-0

In cosmic microwave background （CMB） experiments, foreground-cleaned temperature maps are still contaminated by the resid- ual dipole due to uncertainties of the Doppler dipole direction and microwave radiometer sidelobe. To obtain reliable CMB maps, such contamination has to be carefully removed from observed data. We have previously built a software package for map-making, residual dipole-contamination removal, and power spectrum estimation from the Wilkinson Microwave Anisotropy Probe （WMAP） raw data. This software has now been significantly improved. With the improved software, we obtain a negative result of CMB quadrupole detection with the WMAP raw data, which is -3.2±3.5 μK2 from the seven-year WMAP （WMAP7） data. This result is evidently incompatible with -1000 μK2 expected from the standard cosmological model ACDM. The completely missing of CMB quadrupole poses a serious challenge to the standard model and sets a strong constraint on possible models of cosmology. Due to the importance of this result for understanding the origin and early evolution of our universe, the software codes we used are opened for public checking.