Analysis of WMAP 7 year temperature data: Astrophysics of the galactic haze

Abstract

We perform a joint analysis of the cosmic microwave background (CMB) and Galactic emission from the WMAP 7year temperature data. Using the Commander code, based on Gibbs sampling, we simultaneously derive the CMB and Galactic components on scales larger than 1° with improved sensitivity over previous work. We conduct a detailed study of the low-frequency Galactic foreground, focusing on the "microwave haze" emission around the Galactic center. We demonstrate improved performance in quantifying the diffuse Galactic emission when including Haslam 408MHz data and when jointly modeling the spinning and thermal dust emission. We examine whether the hypothetical Galactic haze can be explained by a spatial variation of the synchrotron spectral index, and find that the excess of emission around the Galactic center is stable with respect to variations of the foreground model. Our results demonstrate that the new Galactic foreground component - the microwave haze - is indeed present. © 2012 The American Astronomical Society. All rights reserved.