Cosmological Implications of the CMB Large-Scale Structure

Abstract

The Wilkinson Microwave Anisotropy Probe (WMAP) and Planck may have uncovered several anomalies in the full cosmic microwave background (CMB) sky that 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 LCDM model where the CMB is described by a Gaussian Random Field, the quadrupole and octopole moments should be statistically independent. 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, and ignoring the biasing due to posterior selection, the missing large-angle correlations would have a probability as low as ∼0.1% and the low-l multipole alignment would be unlikely at the ∼4.9% level; under the least favorable conditions, their simultaneous observation in the context of the standard model could then be likely at only the ∼0.005% level. In this paper, we explore the possibility that these features are indeed anomalous, and show that the corresponding probability of CMB multipole alignment in the = R ct h universe would then be ∼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 ⩾7%, much more likely than in LCDM, 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.

Alcock–Paczyński test with model-independent BAO data

“…In light of the AP results, one may begin to question its status as a true 'concordance' model. Instead, the AP test using these model-independent data favors the R h = ct universe, which has thus far also been favored by model selection tools in other one-on-one comparative tests with ΛCDM 41,42,43,44,45,46,47,48,53,54 . The consequences of this important result are being explored elsewhere, including the growing possibility that inflation may have been unnecessary to resolve any perceived 'horizon problem' and therefore may have simply never happened 43 .…”

“…The R h = ct model represents a cosmology with zero 'active mass,' i.e., with the equation of state ρ + 3p = 0, where ρ and p are, respectively, the total density and pressure of the cosmic fluid. This model has successfully passed all other cosmological tests applied to it thus far 41,42,43,44,45,46,47,48 , though there remain some observations to be understood. Table 1.…”

Power law cosmology model comparison with CMB scale information

“…From a theoretical point of view, there is also some controversy on the motivation for such models [10][11][12][13]. As in the general power law case, some studies claimed that this model is ruled out by observations [8,14], while some others claimed that R h = ct is able to fit the data even better than ΛCDM [15], and that it can explain a large amount of physics like the epoch of reionization [16], the highredshift quasars [17], the cosmic microwave background (CMB) multipole alignment [18] or the constancy of the cluster gas mass fraction [19].…”

Tests and Problems of the Standard Model in Cosmology

“…If there were no such contamination and the tension of the low quadrupole, the low octopole, and the alignment of the quadrupole and octopole were real, the tension could be alleviated with a different cosmological model; for instance, R h = ct cosmology [291].…”