Baryon oscillations in galaxy and matter power-spectrum covariance matrices
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We investigate large-amplitude baryon acoustic oscillations (BAO's) in off-diagonal entries of cosmological power-spectrum covariance matrices. These covariance-matrix BAO's describe the increased attenuation of power-spectrum BAO's caused by upward fluctuations in large-scale power. We derive an analytic approximation to covariance-matrix entries in the BAO regime, and check the analytical predictions using N-body simulations. These BAO's look much stronger than the BAO's in the power spectrum, but seem detectable only at about a one-sigma level in gigaparsec-scale galaxy surveys. In estimating cosmological parameters using matter or galaxy power spectra, including the covariance-matrix BAO's can have a several-percent effect on error-bar widths for some parameters directly related to the BAO's, such as the baryon fraction. Also, we find that including the numerous galaxies in small haloes in a survey can reduce error bars in these cosmological parameters more than the simple reduction in shot noise might suggest.
11 pages, 11 figures, accepted to MNRAS. Minor changes to match accepted version. CosmoPy (Cosmological Python) code available at http://ifa.hawaii.edu/cosmopy/
11 pages, 11 figures, accepted to MNRAS. Minor changes to match accepted version. CosmoPy (Cosmological Python) code available at http://ifa.hawaii.edu/cosmopy/