COSMOLOGICAL IMPLICATIONS OF THE CMB LARGE-SCALE STRUCTURE
The Wilkinson Microwave Anisotropy Probe (WMAP) and {\it Planck} {\bf may have} uncovered several anomalies in the full cosmic microwave background (CMB) sky that {\bf could indicate} possible new physics driving the growth of density fluctuations in the early Universe. These include an unusually...
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Language: | en |
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IOP PUBLISHING LTD
2014
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Online Access: | http://hdl.handle.net/10150/615117 http://arizona.openrepository.com/arizona/handle/10150/615117 |
Summary: | The Wilkinson Microwave Anisotropy Probe (WMAP) and {\it Planck} {\bf may have}
uncovered several anomalies in the full cosmic microwave background (CMB)
sky that {\bf could indicate} possible new physics driving the growth of
density fluctuations in the early Universe. These include an unusually
low power at the largest scales and an apparent alignment of the
quadrupole and octopole moments. In a $\Lambda$CDM model where the
CMB is described by a Gaussian Random Field, the quadrupole and octopole
moments should be statistically independent. {\bf The emergence of these
low probability features may simply be due to posterior selections from
many such possible effects, whose occurrence would therefore not be as unlikely
as one might naively infer. If this is not the case, however, and if these
features are not due to effects such as foreground contamination, their
combined statistical significance would be equal to the product of their
individual significances.} In the absence of such extraneous factors,
{\bf and ignoring the biasing due to posterior selection, the missing large-angle
correlations would have a probability as low as $\sim 0.1\%$ and the
low-$l$ multipole alignment would be unlikely at the $\sim 4.9\%$
level; under the least favourable conditions, their simultaneous observation
in the context of the standard model could then be likely at only
the $\sim 0.005\%$ level.} In this paper, {\bf we explore the possibility
that these features are indeed anomalous, and} show that the
corresponding probability of CMB multipole alignment in the
$R_{\rm h}=ct$ Universe {\bf would then be} $\sim 7-10\%$,
depending on the number of large-scale Sachs-Wolfe
induced fluctuations. Since the low power at the largest spatial
scales is reproduced in this cosmology without the need to invoke
cosmic variance, the overall likelihood of observing both of these
features in the CMB is $\geq 7\%$, {\bf much more likely than in
$\Lambda$CDM, if the anomalies are real.} The key physical ingredient
responsible for this difference is the existence in the former
of a maximum fluctuation size at the time of recombination,
which is absent in the latter because of inflation. |
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