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The C-Band All-Sky Survey (C-BASS) has observed the Galaxy at 4.76 GHz with an angular resolution of 0 |${_{.}^{\circ}}$| 73 full-width half-maximum, and detected Galactic synchrotron emission with high signal-to-noise ratio over the entire northern sky (δ > −15○). We present the results of a spatial correlation analysis of Galactic foregrounds at mid-to-high (b > 10○) Galactic latitudes using a preliminary version of the C-BASS intensity map. We jointly fit for synchrotron, dust, and free–free components between 20 and 1000 GHz and look for differences in the Galactic synchrotron spectrum, and the emissivity of anomalous microwave emission (AME) when using either the C-BASS map or the 408-MHz all-sky map to trace synchrotron emission. We find marginal evidence for a steepening (<Δ β > = −0.06 ± 0.02) of the Galactic synchrotron spectrum at high frequencies resulting in a mean spectral index of < β > = −3.10 ± 0.02 over 4.76–22.8 GHz. Further, we find that the synchrotron emission can be well modelled by a single power law up to a few tens of GHz. Due to this, we find that the AME emissivity is not sensitive to changing the synchrotron tracer from the 408-MHz map to the 4.76-GHz map. We interpret this as strong evidence for the origin of AME being spinning dust emission. [ABSTRACT FROM AUTHOR]

The C-Band All-Sky Survey (C-BASS) is a high sensitivity all-sky radio survey at an angular resolution of 45 arcmin and a frequency of 4.7 GHz. We present a total intensity map of the North Celestial Pole (NCP) region of sky, above declination >+80°, which is limited by source confusion at a level of ≈0.6 mK rms. We apply the template-fitting (cross-correlation) technique to WMAP and Planck data, using the C-BASS map as the synchrotron template, to investigate the contribution of diffuse foreground emission at frequencies ∼20–40 GHz. We quantify the anomalous microwave emission (AME) that is correlated with far-infrared dust emission. The AME amplitude does not change significantly (⁠|${\lt }10\, {{\ \rm per\ cent}}$|⁠) when using the higher frequency C-BASS 4.7 GHz template instead of the traditional Haslam 408 MHz map as a tracer of synchrotron radiation. We measure template coefficients of 9.93 ± 0.35 and |$9.52\pm 0.34\,$|  K per unit τ353 when using the Haslam and C-BASS synchrotron templates, respectively. The AME contributes |$55\pm 2\, \mu$| K rms at 22.8 GHz and accounts for |${\approx } 60{{\ \rm per\ cent}}$| of the total foreground emission. Our results show that a harder (flatter spectrum) component of synchrotron emission is not dominant at frequencies ≳5 GHz; the best-fitting synchrotron temperature spectral index is β = −2.91 ± 0.04 from 4.7 to 22.8 GHz and β = −2.85 ± 0.14 from 22.8 to 44.1 GHz. Free–free emission is weak, contributing |${\approx } 7\, \mu$| K rms (⁠|${\approx } 7{{\ \rm per\ cent}}$|⁠) at 22.8 GHz. The best explanation for the AME is still electric dipole emission from small spinning dust grains. [ABSTRACT FROM AUTHOR]

We present an analysis of the diffuse emission at 5 GHz in the first quadrant of the Galactic plane using two months of preliminary intensity data taken with the C-Band All-Sky Survey (C-BASS) northern instrument at the Owens Valley Radio Observatory, California. Combining C-BASS maps with ancillary data tomake temperature.temperature plots, we find synchrotron spectral indices of β = .2.65 } 0.05 between 0.408 and 5 GHz and β = .2.72 } 0.09 between 1.420 and 5 GHz for -10° < |b| < -4°, 20° < l < 40°. Through the subtraction of a radio recombination line free.free template, we determine the synchrotron spectral index in the Galactic plane (|b|<4°) to be β =.2.56±0.07 between 0.408 and 5 GHz, with a contribution of 53±8 per cent from free.free emission at 5 GHz. These results are consistent with previous low-frequency measurements in the Galactic plane. By including C-BASS data in spectral fits, we demonstrate the presence of anomalous microwave emission (AME) associated with the HII complexes W43, W44 and W47 near 30 GHz, at 4.4σ, 3.1σ and 2.5σ, respectively. The CORNISH (Co-Ordinated Radio eNf Infrared Survey for High mass star formation) VLA 5-GHz source catalogue rules out the possibility that the excess emission detected around 30 GHz may be due to ultracompact HII regions. Diffuse AME was also identified at a 4σ level within 30° < l < 40°, -2° < b < 2° between 5 and 22.8 GHz. [ABSTRACT FROM AUTHOR]

ABSTRACT Anomalous microwave emission at 20-40 GHz has been detected across our Galactic sky. It is highly correlated with thermal dust emission and hence it is thought to be due to spinning dust grains. Alternatively, this emission could be due to synchrotron radiation with a flattening (hard) spectral index. We cross-correlate synchrotron, free-free and thermal dust templates with the Wilkinson Microwave Anisotropy Probe ( WMAP) 7-year maps using synchrotron templates at both 408 MHz and 2.3 GHz to assess the amount of flat synchrotron emission that is present, and the impact that this has on the correlations with the other components. We find that there is only a small amount of flattening visible in the synchrotron spectral indices by 2.3 GHz, of around Δβ ≈ 0.05, and that the significant level of dust-correlated emission in the lowest WMAP bands is largely unaffected by the choice of synchrotron template, particularly at high latitudes (it decreases by only ∼7 per cent when using 2.3 GHz rather than 408 MHz). This agrees with expectation if the bulk of the anomalous emission is generated by spinning dust grains. [ABSTRACT FROM AUTHOR]