Year: 2015
Type: article
Abstract: 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 to make 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 H ii complexes W43, W44 and W47 near 30 GHz, at 4.4σ, 3.1σ and 2.5σ, respectively. The CORNISH (Co-Ordinated Radio ‘N’ 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 H ii regions. Diffuse AME was also identified at a 4σ level within 30° < l < 40°, −2° < b < 2° between 5 and 22.8 GHz.
DOI: 10.1093/mnras/stv212
Authors: M. O. Irfan, C. Dickinson, R. D. Davies, C. Copley, R. J. Davis, P. G. Ferreira, C. M. Holler, J. L. Jonas, Michael E. Jones, O. G. King, J. P. Leahy, J. Leech, E. M. Leitch, S. J. C. Muchovej, T. J. Pearson, M. W. Peel, A. C. S. Readhead, M. A. Stevenson, D. Sutton, Angela C. Taylor, J. Zuntz
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: The C-Band All Sky Survey: Separating the Polarization of the Cosmic Microwave Background from Galactic Foregrounds, The C-Band All Sky Survey: Diffuse Galactic Emission and CMB Polarization, Accurate CMB foreground removal for future, ultra-high sensitive CMB experiments., The Radio Universe: astronomy and astrophysics at the Jodrell Bank Centre for Astrophysics 2014-2017, Astrophysics and Planetary Science at Oxford 2013-16, The C-Band All Sky Survey: Diffuse Galactic Emission and CMB Polarization
OpenAlex ID: W1967767484