Does the small CMB quadrupole moment suggest new physics?
Abstract
Motivated by WMAP's confirmation of an anomalously low value of the quadrupole moment of the CMB temperature fluctuations, we investigate the effects on the CMB of cutting off the primordial power spectrum P(k) at low wave numbers. This could arise, for example, from a break in the inflaton potential, a prior period of matter or radiation domination, or an oscillating scalar field which couples to the inflaton. We reanalyze the full WMAP parameter space supplemented by a low-k cutoff for P(k). The temperature correlations by themselves are better fit by a cutoff spectrum, but including the TE temperature-polarization spectrum reduces this preference to a 1.4 sigma effect. Inclusion of large scale structure data does not change the conclusion. If taken seriously, the low-k cutoff is correlated with optical depth so that reionization occurs even earlier than indicated by the WMAP analysis.
Cite
@article{arxiv.astro-ph/0304558,
title = {Does the small CMB quadrupole moment suggest new physics?},
author = {James M. Cline and Patrick Crotty and Julien Lesgourgues},
journal= {arXiv preprint arXiv:astro-ph/0304558},
year = {2009}
}
Comments
10 pages 6 figures; corrected eq. 4.1; clarified discussion explaining apparent discrepancy with WMAP's estimate of low quadrupole significance