Anomalous Microwave Emission from the HII region RCW175
Abstract
We present evidence for anomalous microwave emission in the RCW175 \hii region. Motivated by 33 GHz resolution data from the Very Small Array (VSA), we observed RCW175 at 31 GHz with the Cosmic Background Imager (CBI) at a resolution of . The region consists of two distinct components, G29.0-0.6 and G29.1-0.7, which are detected at high signal-to-noise ratio. The integrated flux density is Jy at 31 GHz, in good agreement with the VSA. The 31 GHz flux density is Jy () above the expected value from optically thin free-free emission based on lower frequency radio data and thermal dust constrained by IRAS and WMAP data. Conventional emission mechanisms such as optically thick emission from ultracompact \hii regions cannot easily account for this excess. We interpret the excess as evidence for electric dipole emission from small spinning dust grains, which does provide an adequate fit to the data.
Cite
@article{arxiv.0807.3985,
title = {Anomalous Microwave Emission from the HII region RCW175},
author = {C. Dickinson and R. D. Davies and J. R. Allison and J. R. Bond and S. Casassus and K. Cleary and R. J. Davis and M. E. Jones and B. S. Mason and S. T. Myers and T. J. Pearson and A. C. S. Readhead and J. L. Sievers and A. C. Taylor and M. Todorovic and G. J. White and P. N. Wilkinson},
journal= {arXiv preprint arXiv:0807.3985},
year = {2011}
}
Comments
5 pages, 2 figures, submmited to ApJ Letters