Polarized Diffuse Emission at 2.3 GHz in a High Galactic Latitude Area

Abstract

Polarized diffuse emission observations at 2.3 GHz in a high Galactic latitude area are presented. The 2\degr X 2\degr field, centred in (α=5^h,δ=-49\degr), is located in the region observed by the BOOMERanG experiment. Our observations has been carried out with the Parkes Radio telescope and represent the highest frequency detection done to date in low emission areas. Because of a weaker Faraday rotation action, the high frequency allows an estimate of the Galactic synchrotron contamination of the Cosmic Microwave Background Polarization (CMBP) that is more reliable than that done at 1.4 GHz. We find that the angular power spectra of the E- and B-modes have slopes of β_E = -1.46 +/- 0.14 and β_B = -1.87 +/- 0.22, indicating a flattening with respect to 1.4 GHz. Extrapolated up to 32 GHz, the E-mode spectrum is about 3 orders of magnitude lower than that of the CMBP, allowing a clean detection even at this frequency. The best improvement concerns the B-mode, for which our single-dish observations provide the first estimate of the contamination on angular scales close to the CMBP peak (about 2 degrees). We find that the CMBP B-mode should be stronger than synchrotron contamination at 90 GHz for models with T/S > 0.01. This low level could move down to 60-70 GHz the optimal window for CMBP measures.

5 pages, 6 figures, accepted for publication in MNRAS Letters

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• Detectability of tensor modes in the presence of foregrounds
• The Parkes Galactic Meridian Survey (PGMS): observations and CMB polarization foreground analysis
• 1.4 GHz polarimetric observations of the two fields imaged by the DASI experiment
• Deep 1.4-GHz observations of diffuse polarized emission
• Growing Supermassive Black Holes by Chaotic Accretion
• A novel technique for wide-field polarimetry with a radiotelescope array