Band-power reconstruction of the primordial fluctuation spectrum by the maximum likelihood reconstruction method

The primordial curvature fluctuation spectrum is reconstructed by the maximum likelihood reconstruction method using the five-year Wilkinson Microwave Anisotropy Probe data of the cosmic microwave background temperature anisotropy. We apply the covariance matrix analysis and decompose the reconstructed spectrum into statistically independent band powers. The prominent peak off a simple power-law spectrum found in our previous analysis turn out to be a 3.3 sigma deviation. From the statistics of primordial spectra reconstructed from mock observations, the probability that a primordial spectrum including such excess is realized in a power-law model is estimated to be about 2%.