Polarized diffuse emission at 2.3 GHz in a high Galactic latitude area

被引:9
作者
Carretti, E
McConnell, D
McClure-Griffiths, NM
Bernardi, G
Cortiglioni, S
Poppi, S
机构
[1] INAF, IASF Bologna, I-40129 Bologna, Italy
[2] CSIRO, Australia Telescope Natl Facil, Epping, NSW 1710, Australia
[3] INAF, IRA Bologna, I-40129 Bologna, Italy
关键词
polarization; radiation mechanisms : non-thermal; cosmic microwave background; diffuse radiation; radio continuum : ISM;
D O I
10.1111/j.1745-3933.2005.00034.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Polarized diffuse emission observations at 2.3 GHz in a high Galactic latitude area are presented. The 2 degrees x 2 degrees field, centred at (alpha= 5(h), delta=-49 degrees), is located in the region observed by the BOOMERanG experiment. Our observations were carried out with the Parkes radio telescope, and represent the highest frequency detection to date in a low-emission area. Because of the weaker Faraday rotation effect, the high frequency allows an estimate of the Galactic synchrotron contamination of the cosmic microwave background polarization (CMBP) which is more reliable than that achieved at 1.4 GHz. We find that the angular power spectra of the E- and B-modes have slopes of beta(E) = -1.46 +/- 0.14 and beta(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 three 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 the synchrotron contamination at 90 GHz for models with tensor-to-scalar perturbation ratio T/S > 0.01. This low level could move down to 60-70 GHz the optimal window for CMBP measurements.
引用
收藏
页码:L10 / L14
页数:5
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