The authors study the dip in the CMB angular power spectrum around [tex]\ell\sim200[/tex] which was noted in the first year WMAP data. They find that removing a 30 degree region around the north ecliptic pole increases the power in this multipole range. The significance varies from 96% to 99.5% depending on the data (WMAP1, WMAP3 or WMAP5) and the noise weighting scheme used.
This is to be compared to astro-ph/0404206, where Hansen et al studied 19 degree discs and found no angular dependence of the first peak position and amplitude.
[1005.5389] Degree-scale anomalies in the CMB: localizing the first peak dip to a small patch of the north ecliptic sky
|Authors:||Amanda Yoho, Francesc Ferrer, Glenn D. Starkman|
|Abstract:||Noticeable deviations from the prediction of the fiducial LCDM cosmology are found in the angular power spectrum of the CMB. Besides large-angle anomalies, the WMAP 1st year data revealed a dip in the power spectrum at l \sim 200, which seemed to disappear in the 3rd year and subsequent angular power spectra. Using the WMAP 1st, 3rd, and 5th year data release, we study the intensity and spatial distribution of this feature in order to unveil its origin and its implications for the cosmological parameters. We show that in all WMAP data releases there is a substantial suppression of the first Doppler peak in a region near the north ecliptic pole.|
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