On the influence of local inhomogeneities on cosmological observables

Abstract

Despite the good consistency of the cosmological standard model with the bulk of present observations, a number of unanticipated features have recently been detected within large-angle data of the Cosmic Microwave Background. Among these features are the anomalous alignments of the quadrupole and octopole with each other, their unexpected alignments with certain astrophysical directions (e.g. equinox, ecliptic) as well as the stubborn lack of angular autocorrelation on scales > 60ʿ. We pursue the idea that processes of non-linear structure formation could contribute to the large-scale anomalies via a local Rees-Sciama effect. We find that existing structures are able to produce CMB contributions up to 10^-5. For an axially symmetric setup we show that this effect does induce alignments, albeit not of the same form as extracted from the data, and that yet a Solar system effect seems preferred by the data. Moreover, we address the relationship between the intrinsic alignment of quadrupole and octopole on the one hand and the anomalous angular two-point correlation function on the other hand. We demonstrate the absence of any correlations between them and are able to exclude the joint case at high confidence with respect to recent data. This result enables us to put stringent constraints on any relevant model that exhibits an explicit axial symmetry.