Significant Foreground Unrelated Non-Acoustic Anisotropy on the 1 Degree Scale in Wilkinson Microwave Anisotropy Probe 5-Year Observations

Type Journal Article
Names Bi-Zhu Jiang, Richard Lieu, Shuang-Nan Zhang, Bart Wakker
Publication The Astrophysical Journal
Volume 708
Issue 1
Pages 375-380
Date January 1, 2010
Library Catalog NASA ADS
Abstract The spectral variation of the cosmic microwave background (CMB) as observed by WMAP was tested using foreground reduced WMAP5 data, by producing subtraction maps at the 1° angular resolution between the two cosmological bands of V and W, for masked sky areas that avoid the Galactic disk. The resulting V - W map revealed a non-acoustic signal over and above the WMAP5 pixel noise, with two main properties. First, it possesses quadrupole power at the ≈1 μK level which may be attributed to foreground residuals. Second, it fluctuates also at all values of ell> 2, especially on the 1° scale (200 lsim ell lsim 300). The behavior is random and symmetrical about zero temperature with an rms ≈7 μK, or 10% of the maximum CMB anisotropy, which would require a "cosmic conspiracy" among the foreground components if it is a consequence of their existence. Both anomalies must be properly diagnosed and corrected if "precision" cosmology is the claim. The second anomaly is, however, more interesting because it opens the question on whether the CMB anisotropy genuinely represents primordial density seeds.
Tags ISM: clouds, cosmic microwave background, methods: data analysis
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