Submillimeter polarization of Galactic clouds: a comparison of 350 µm and 850 µm data.
VAILLANCOURT J.E. and MATTHEWS B.C.
Abstract (from CDS):
The Hertz and SCUBA polarimeters, working at 350 µm and 850 µm, respectively, have measured the polarized emission in scores of Galactic clouds. Of the clouds in each data set, 17 were mapped by both instruments with good polarization signal-to-noise ratios. We present maps of each of these 17 clouds comparing the dual-wavelength polarization amplitudes and position angles at the same spatial locations. In total number of clouds compared, this is a four-fold increase over previous work. Across the entire data set real position angle differences are seen between wavelengths. While the distribution of φ(850)-φ(350) is centered near zero (near-equal angles), 64% of data points with high polarization signal-to-noise (P ≥ 3σp) have|φ(850)-φ(350)| > 10°. Of those data with small changes in position angle ( ≤ 10°) the median ratio of the polarization amplitudes is P(850)/P(350) = 1.7±0.6. This value is consistent with previous work performed on smaller samples and models that require mixtures of different grain properties and polarization efficiencies. Along with the polarization data we have also compiled the intensity data at both wavelengths; we find a trend of decreasing polarization with increasing 850-to-350 µm intensity ratio. All the polarization and intensity data presented here (1699 points in total) are available in electronic format.