Simulations of Baryon Acoustic Oscillations: Likelihood Analysis of the Matter Power Spectrum

We study the sample variance of the matter power spectrum for the standard Λ Cold Dark Matter universe. We use a total of 5000 cosmological N-body cosmological simulations to study the cosmological parameter estimations using the Fisher matrix analysis with and without including non-Gaussian errors. For the Fisher matrix analysis, we compute the derivatives of the matter power spectrum with respect to cosmological parameters using directly full nonlinear simulations. We show that the non-Gaussian errors increase the unmarginalized errors by up to a factor 5 for kmax = 0.4h/Mpc if there is only one free parameter (if other parameters are well determined by external information). On the other hand, for multi-parameter fitting, the impact of the non-Gaussian errors is significantly mitigated due to severe parameter degeneracies in the power spectrum