COSMOSOMAS Results. Polarization Observations of the Anomalous Emission
The anomalous microwave emission detected in the Perseus molecular complex by Watson et al. (2005) has been observed at 11 GHz through dual-orthogonal polarizations in the COSMOSOMAS experiment. The results of this study can be found in Battistelli et al. (2006). Stokes Q and U maps are obtained at a resolution of ~0.9° for a 30° x 30° region including the Perseus Molecular complex (see color figure below). A faint polarized emission has been measured, with an overall polarization parameter of
Π = 3.4^{+1.5}_{-1.9} (95% C.L.)
with a 1.0 % systematic uncertainty determined by testing the instrument performance using unpolarized sources in our map as a null test. These are the first constraints on the polarization properties of an anomalous microwave emission source. The low level of polarization seems to indicate that the particles responsible for this emission in the Perseus molecular complex are not significantly aligned in a common direction over the whole region due to either a highly structural symmetry of the emitting particle, or to a low-intensity magnetic field. Our weak detection is fully consistent with the predictions from electric dipole emission and resonance relaxation at this frequency.
(March 2006)