2003/06/30 by Patrick Dineen, Peter Coles · 1 citation
Physics and Astronomy · #Cosmology and Gravitation Theories #Radio Astronomy Observations and Technology #Scientific Research and Discoveries #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2004.07241.x
published as Mon.Not.Roy.Astron.Soc.347:52,2004 · 8 pages, 1 figure, accepted for publication in MNRAS
arxiv created 2003/08/12 · openalex publication_date 2003/12/15 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a diagnostic test of possible Galactic contamination of cosmic microwave background (CMB) sky maps designed to provide an independent check on the methods used to compile these maps. The method involves a non-parametric measurement of cross-correlation between the Faraday rotation measure (RM) of extragalactic sources and the measured microwave signal at the same angular position. We argue that statistical properties of the observed distribution of rotation measures are consistent with a Galactic origin, an argument reinforced by a direct measurement of cross-correlation between the dust, free–free and synchrotron foreground maps and the RM values, with the strongest correlation being for dust and free–free. We do not find any statistically compelling evidence for correlations between the RM values and the COBE Differential Microwave Radiometer (DMR) maps at any frequency, so there is no evidence of residual contamination in these CMB maps. On the other hand, there is a statistically significant correlation of RM with the preliminary Wilkinson Microwave Anisotropy Probe (WMAP) individual frequency maps which remains significant in the Tegmark et al. Wiener-filtered map, but not in the internal linear combination map produced by the WMAP team.