paper

Statistical anisotropy of CMB as a probe of conformal rolling scenario

arXiv:1202.4357 · doi:10.1088/1475-7516/2012/05/033

Abstract

Search for the statistical anisotropy in the CMB data is a powerful tool for constraining models of the early Universe. In this paper we focus on the recently proposed cosmological scenario with conformal rolling. We consider two sub-scenarios, one of which involves a long intermediate stage between conformal rolling and conventional hot epoch. Primordial scalar perturbations generated within these sub-scenarios have different direction-dependent power spectra, both characterized by a single parameter h^2. We search for the signatures of this anisotropy in the seven-year WMAP data using quadratic maximum likelihood method, first applied for similar purposes by Hanson and Lewis. We confirm the large quadrupole anisotropy detected in V and W bands, which has been argued to originate from systematic effects rather than from cosmology. We construct an estimator for the parameter h^2. In the case of the sub-scenario with the intermediate stage we set an upper limit h^2 < 0.045 at the 95% confidence level. The constraint on h^2 is much weaker in the case of another sub-scenario, where the intermediate stage is absent.

27 pages, 4 figures. Stronger constraint in case of sub-scenario A obtained. Version accepted for publication in JCAP

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