Growth of correlations in the real space power spectrum

P(k) errors

The number of degrees-of-freedom expected in each frequency band based on counting modes in the simulation box (squares) vs the equivalent number ndof found in the simulations (circles). Also shown are maximum-likelihood estimates of ndof given by fitting the power spectra to a &chi2 distribution (crosses). Correlations between modes reduce the effective number of degrees-of-freedom at high frequencies, and so increase the dispersion in the band-averaged power spectrum estimates over the expectation for uncorrelated modes. (From Meiksin & White 1999, MNRAS, 308, 1179.)

Return to non-linear P(k) correlations