2004/03/12 by G. Bernardi, E. Carretti, R. Fabbri +4 · 3 citations
Physics and Astronomy · #Cosmology and Gravitation Theories #Particle physics theoretical and experimental studies #Radio Astronomy Observations and Technology #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2004.07797.x
published as Mon.Not.Roy.Astron.Soc. 351 (2004) 436 · 13 pages, 14 figures, accepted for pubblications by MNRAS. For a version with full resolution color figures see http://sp0rt.bo.iasf.cnr.it:8080/Docs/Public/papers.php
arxiv created 2004/03/12 · openalex publication_date 2004/06/11 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We build template maps for the polarized Galactic synchrotron emission on large angular scales (7° full width at half maximum), in the 20–90 GHz microwave range, by using Wilkinson Microwave Anisotropy Probe (WMAP) data. The method, presented in recent work, requires a synchrotron total-intensity survey and the polarization horizon to model the polarized intensity and a starlight polarization map to model polarization angles. The basic template is obtained directly at 23 GHz with about 94 per cent sky coverage by using the synchrotron map released by the WMAP team. Extrapolations to 32, 60 and 90 GHz are performed by computing a synchrotron spectral-index map, which strongly reduces previous uncertainties in passing from low (1.4 GHz) to microwave frequencies. Differing from low-frequency data, none of our templates present relevant structures out of the Galactic plane. Our map at 90 GHz suggests that the synchrotron emission at high Galactic latitudes is low enough to allow robust detection of the E-mode component of the cosmological signal on large scale, even in models with low reionization (τ= 0.05). Detection of the weaker B-mode on the largest scales (ℓ < 10) might be jeopardized unless the value τ= 0.17 found by WMAP is confirmed, and tensor-to-scalar fluctuation power ratio T/S > 0.1. For lower levels of the gravitational-wave background the B-mode seems to be accessible only at the ℓ∼ 100 peak and in selected low-synchrotron emission areas.