Abstract
We measure the 2-1 cumulant correlator power spectrum C
, a degenerate bispectrum, from the second data release of the Wilkinson Microwave Anisotropy Probe (WMAP). Our high-resolution measurements with SpICE span a large configuration space (≃168 × 999) corresponding to the possible cross-correlations of the maps recorded by the different differencing assemblies. We present a novel method to recover the eigenmodes of the correspondingly large Monte Carlo covariance matrix. We examine its eigenvalue spectrum and use random matrix theory to show that the off-diagonal terms are dominated by noise. We minimize the χ2 to obtain constraints for the nonlinear coupling parameter fNL = 22 ± 52 (1 σ).
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