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Advances in Astronomy
Volume 2012 (2012), Article ID 853927, 8 pages
Research Article

Spectrum of the Anomalous Microwave Emission in the North Celestial Pole with WMAP 7-Year Data

1Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, the University of Manchester, Alan Turing Building, Oxford Road, Manchester M13 9PL, UK
2INAF-IASF Bologna, Via Gobetti 101, Bologna, Italy

Received 30 July 2012; Accepted 3 December 2012

Academic Editor: Clive Dickinson

Copyright © 2012 Anna Bonaldi and Sara Ricciardi. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We estimate the frequency spectrum of the diffuse anomalous microwave emission (AME) on the North Celestial Pole (NCP) region of the sky with the Correlated Component Analysis (CCA) component separation method applied to WMAP 7-yr data. The NCP is a suitable region for this analysis because the AME is weakly contaminated by synchrotron and free-free emission. By modeling the AME component as a peaked spectrum we estimate the peak frequency to be  GHz, in agreement with previous analyses which favored < 23 GHz. The ability of our method to correctly recover the position of the peak is verified through simulations. We compare the estimated AME spectrum with theoretical spinning dust models to constrain the hydrogen density . The best results are obtained with densities around 0.2–0.3 cm−3, typical of warm ionised medium (WIM) to warm neutral medium (WNM) conditions. The degeneracy with the gas temperature prevents an accurate determination of , especially for low hydrogen ionization fractions, where densities of a few cm−3 are also allowed.