We use 5000 cosmological N-body simulations of 1 h-3 Gpc3 box for the concordance ËCDM model in order to study the sampling variances of a nonlinear matter power spectrum. We show that the non-Gaussian errors can be important even on large length scales relevant for baryon acoustic oscillations (BAOs). Our findings are the following: (1) the non-Gaussian errors degrade the cumulative signal-to-noise ratios (S/Ns) for the power spectrum amplitude by up to a factor of 2 and 4 for redshifts z = 1 and 0, respectively; (2) there is little information on the power spectrum amplitudes in the quasi-nonlinear regime, confirming the previous results; (3) the distribution of power spectrum estimators at BAO scales, among the realizations, is well approximated by a Gaussian distribution with variance that is given by the diagonal covariance component. (4) For the redshiftspace power spectrum, the degradation in S/N by non-Gaussian errors is mitigated due to nonlinear redshift distortions; (5) for an actual galaxy survey, the additional shot noise contamination compromises the cosmological information inherent in the galaxy power spectrum, but also mitigates the impact of non-Gaussian errors. The S/N is degraded by up to 30% for aWide-Field Fiber-Fed Optical Multi-Object Spectrograph-type survey; (6) the finite survey volume causes additional non-Gaussian errors via the correlations of long-wavelength fluctuations with the fluctuations we want to measure, further degrading the S/N values by about 30% even at high redshift z = 3.
R. Takahashi and N. Yoshida and M. Takada and T. Matsubara and N. Sugiyama and I. Kayo and A. J. Nishizawa and T. Nishimichi and S. Saito and A. Taruya, "Simulations of Baryon Acoustic Oscillations. II. Covariance Matrix of the Matter Power Spectrum," Astrophysical Journal, vol. 700, no. 1, pp. 479-490, Institute of Physics - IOP Publishing, Jul 2009.
The definitive version is available at https://doi.org/10.1088/0004-637X/700/1/479
Keywords and Phrases
Cosmology: theory; Large-scale structure of universe
International Standard Serial Number (ISSN)
Article - Journal
© 2009 The American Astronomical Society, All rights reserved.
01 Jul 2009