Nonlinear matter clustering properties of a cold dark matter universe

Abstract

view Abstract Citations (65) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Nonlinear Matter Clustering Properties of a Cold Dark Matter Universe Bouchet, Francois R. ; Schaeffer, Richard ; Davis, Marc Abstract We study the matter distribution of strongly nonlinear scales in a CDM model. To that effect, we determine the count probabilities in an unbiased catalog generated with a P^3^M simulation code (Davis & Efstathiou) and compare the results with the predictions of the scale- invariant model introduced by Balian and Schaeffer and those of the thermodynamical model introduced by Saslaw. We find that the probability P_N_ of finding a given amount of matter, i.e., N particles in a specified volume, is a power law with a lower and an upper cutoff. These cuts may be described for all volume sizes by two universal functions that we determine, in the proper limit of a continuous distribution. These results show that such a CDM simulation indeed presents all the count probability properties expected from a scale-invariant system. On the other hand, we find that all the specific scale-invariant models proposed by various authors can be confidently rejected. We propose a phenomenological model which is compatible with the data as well as with all the theoretical constraints. We also find that the thermodynamical model of Saslaw reproduces the qualitative features of the results of the simulations, provided we adjust to each case the free parameter b of this model, which ought to be unique. In particular, three different scale-dependent choices are seen to be necessary to reproduce, respectively, the void probability function, the matter fluctuations in a given cell, and the exponential falloff of the count probability P_N_ at large N. In other words, no overall fit could be obtained for small and large N simultaneously, the discrepancy being worse at the small, more nonlinear scales which should be the most virialized. The main reason for this failure is that the thermodynamic approach does not provide for the scale-invariant properties that are seen to hold in the numerical simulations. This precludes the use of this approach to describe the matter distribution in a CDM universe. Publication: The Astrophysical Journal Pub Date: December 1991 DOI: 10.1086/170759 Bibcode: 1991ApJ...383...19B Keywords: Cosmology; Dark Matter; Galactic Clusters; Scaling Laws; Universe; Mathematical Models; Nonlinearity; Probability Density Functions; Spatial Distribution; Astrophysics; COSMOLOGY; DARK MATTER; GALAXIES: CLUSTERING full text sources ADS |