C126 ガウス的初期条件における宇宙論的密度ゆらぎの確率分布関数

概要

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We quantitatively study the probability distribution function (PDF) of cosmological nonlinear density fluctuations from N-body simulations with Gaussian initial condition. With a particular attention to the validity and limitations of empirical log-normal PDF model against the PDF directly estimated from the simulations, we find that the log-normal PDF describes very accurately the cosmological density distribution even in the nonlinear regime (the rms variance σ_<nl>≲4 and the over-density δ≲100). Thus the log-normal PDF can be used as a useful empirical model for the cosmological density fluctuations. On the contrary, the one-to-one mapping of the initial and the evolved density fields consistent with the log-normal model does not approximate the broad distribution of their mutual correlation even on average.
2001-07-31