Angular correlation of the cosmic microwave background in the R _h = ct Universe

Context. The emergence of several unexpected large-scale features in the cosmic microwave background (CMB) has pointed to possible new physics driving the origin of density fluctuations in the early Universe and their evolution into the large-scale structure we see today. Aims. In this paper, we focus our attention on the possible absence of angular correlation in the CMB anisotropies at angles larger than ~60, and consider whether this feature may be the signature of fluctuations expected in the R_h = ct Universe. Methods. We calculate the CMB angular correlation function for a fluctuation spectrum expected from growth in a Universe whose dynamics is constrained by the equation-of-state p =-ρ/3, where p and ρ are the total pressure and density, respectively. Results. We find that, though the disparity between the predictions of ΛCDM and the WMAP sky may be due to cosmic variance, it may also be due to an absence of inflation. The classic horizon problem does not exist in the R_h = ct Universe, so a period of exponential growth was not necessary in this cosmology in order to account for the general uniformity of the CMB (save for the aforementioned tiny fluctuations of 1 part in 100 000 in the WMAP relic signal). Conclusions. We show that the R_h = ct Universe without inflation can account for the apparent absence in CMB angular correlation at angles θ ≠60 without invoking cosmic variance, providing additional motivation for pursuing this cosmology as a viable description of nature.