**AAS 203rd Meeting, January 2004**

*Session 82 Mass and Energy Matters*

Poster, Wednesday, January 7, 2004, 9:20am-6:30pm, Grand Hall
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## [82.06] Covariance of the One-dimensional Mass Power Spectrum

*H. Zhan (Dept of Physics, University of Arizona), D. Eisenstein (Steward Observatory, University of Arizona)*

We provide an analysis of the covariance of the
one-dimensional mass power spectrum. The covariance reveals
the correlation between different wavenumbers in the cosmic
density field, and gives the sample variance error for
measurements of the power spectrum from limited observations
such as the Ly\alpha forest. For Gaussian random fields,
the covariance matrix is diagonal. As expected, the variance
of the measured one-dimensional power spectrum is inversely
proportional to the number of lines of sight that are
sampled from each random field -- assuming they are well
separated. Using N-body simulations, we find that the
covariance matrix of the one-dimensional power spectrum is
generally not diagonal for the cosmic density field due to
non-Gaussianity and that the variance is higher than that of
a Gaussian random field. We quantify the effects of
non-Gaussianity as a function of the separation between the
lines of sight. Once the covariance is known, one can not
only determine the cosmic variance in the measured
one-dimensional power spectrum but also estimate how many
lines of sight are needed to achieve a given accuracy.

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Bulletin of the American Astronomical Society, **35**#5

© 2003. The American Astronomical Soceity.