Cosmic Microwave Background Statistics for a Direction-Dependent Primordial Power Spectrum
Abstract
Statistical isotropy of primordial perturbations is a common assumption in cosmology, but it is an assumption that should be tested. To this end, we develop cosmic microwave background statistics for a primordial power spectrum that depends on the direction, as well as the magnitude, of the Fourier wavevector. We first consider a simple estimator that searches in a model-independent way for anisotropy in the square of the temperature (and/or polarization) fluctuation. We then construct the minimum-variance estimators for the coefficients of a spherical-harmonic expansion of the direction-dependence of the primordial power spectrum. To illustrate, we apply these statistics to an inflation model with a quadrupole dependence of the primordial power spectrum on direction and find that a power quadrupole as small as 2.0% can be detected with the Planck satellite.
Cite
@article{arxiv.0709.1144,
title = {Cosmic Microwave Background Statistics for a Direction-Dependent Primordial Power Spectrum},
author = {Anthony R. Pullen and Marc Kamionkowski},
journal= {arXiv preprint arXiv:0709.1144},
year = {2008}
}
Comments
Published in Phys. Rev. D; 8 pages; 1 table; Table 1 corrected; references added