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2012MNRAS.422.3617G - Mon. Not. R. Astron. Soc., 422, 3617-3642 (2012/June-1)
Foreground analysis using cross-correlations of external templates on the 7-year Wilkinson Microwave Anisotropy Probe data.
GHOSH T., BANDAY A.J., JAFFE T., DICKINSON C., DAVIES R., DAVIS R. and GORSKI K.
Abstract (from CDS):
The synchrotron emission shows evidence of steepening between GHz frequencies and the WMAP bands. There are indications of spectral index variations across the sky, but the current data are not precise enough to accurately quantify this from region to region.
The Hα template correlated emission derived from the global fits shows clear evidence of deviation from a free-free spectrum. If this spectrum is decomposed into a contribution from both free-free and spinning dust emission in the warm ionized medium of the Galaxy, the derived free-free emissivity corresponds to a mean electron temperature of ∼6000 K (a value critically dependent on the impact of dust absorption on the Hα intensity), and the spinning dust emission has a peak emission in intensity typically in the range 40-50 GHz. However, the analysis of the smaller regions is generally unrevealing and the analysis presented here does not unambiguously demonstrate the presence of spinning dust emission in the warm ionized medium, as advocated by Dobler & Finkbeiner.
The anomalous microwave emission associated with dust is detected at high significance in most of the 33 fields studied. The anomalous emission correlates well with the Finkbeiner et al. model 8 predictions (FDS8) at 94 GHz, and is well described globally by a power-law emission model with an effective spectral index between 20 and 60 GHz of β ≈ -2.7. It is clear that attempts to explain the emission by spinning dust models require multiple components, which presumably relates to a complex mix of emission regions along a given line of sight. An enhancement of the thermal dust contribution over the FDS8 predictions by a factor ∼1.2 is required with such models. Furthermore, the emissivity varies by a factor of ∼50 per cent from cloud to cloud relative to the mean.
The significance of these results for the correction of cosmic microwave background data for Galactic foreground emission is discussed.
Abstract Copyright: 2012 The Authors Monthly Notices of the Royal Astronomical Society2012 RAS
Journal keyword(s): radiation mechanisms: general - cosmology: observations - diffuse radiation - radio continuum: ISM
Simbad objects: 10
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