Multipole Vector Anomalies in the FirstYear WMAP Data: A CutSky Analysis
Abstract
We apply the recently defined multipole vector framework to the frequencyspecific firstyear WMAP sky maps, estimating the lowl multipole coefficients from the highlatitude sky by means of a power equalization filter. While most previous analyses of this type have considered only heavily processed (and foregroundcontaminated) fullsky maps, the present approach allows for greater control of residual foregrounds and therefore potentially also for cosmologically important conclusions. The lowl spherical harmonic coefficients and corresponding multipole vectors are tabulated for easy reference. Using this formalism, we reassess a set of earlier claims of both cosmological and noncosmological lowl correlations on the basis of multipole vectors. First, we show that the apparent l=3 and 8 correlation claimed by Copi and coworkers is present only in the heavily processed map produced by Tegmark and coworkers and must therefore be considered an artifact of that map. Second, the wellknown quadrupoleoctopole correlation is confirmed at the 99% significance level and shown to be robust with respect to frequency and sky cut. Previous claims are thus supported by our analysis. Finally, the lowl alignment with respect to the ecliptic claimed by Schwarz and coworkers is nominally confirmed in this analysis, but also shown to be very dependent on severe a posteriori choices. Indeed, we show that given the peculiar quadrupoleoctopole arrangement, finding such a strong alignment with the ecliptic is not unusual.
 Publication:

The Astrophysical Journal
 Pub Date:
 December 2005
 DOI:
 10.1086/497263
 arXiv:
 arXiv:astroph/0507186
 Bibcode:
 2005ApJ...635..750B
 Keywords:

 Cosmology: Cosmic Microwave Background;
 Cosmology: Observations;
 Methods: Numerical;
 Astrophysics
 EPrint:
 13 pages, 2 figures