2003/10/31 by Takayuki Tatekawa · 7 citations
Physics and Astronomy · #Classical mechanics #Cosmology and Gravitation Theories #Exponent #Galaxies: Formation, Evolution, Phenomena #Nonlinear system #Perturbation (astronomy) #Perturbation theory (quantum mechanics) #Physics #Polytrope #Polytropic process #Quantum mechanics #Statistical physics #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1103/physrevd.69.084020
published in Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields 69(8) (American Physical Society) · 23 pages, 9 figures; some figures are replaced; accepted for publication in Phys.Rev.D
arxiv created 2004/01/27 · openalex publication_date 2004/04/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We analyze the performance of a perturbation theory for nonlinear cosmological dynamics, based on the Lagrangian description of hydrodynamics. In our previous paper, we solved the hydrodynamic equations for a self-gravitating fluid with pressure, given by a polytropic equation of state, using a perturbation method. Then we obtained the first-order solutions in generic background universes and the second-order solutions for a wider range of polytrope exponents. Using these results, we describe density fields with a scale-free spectrum, SCDM, and LCDM models. Then we analyze the cross-correlation coefficient of the density field between N-body simulation and Lagrangian linear perturbation theory, and the probability distribution of the density fluctuations. From our analyses, for scale-free spectrum models, the case of the polytrope exponent 5/3 shows better performance than the Zel'dovich approximation and the truncated Zel'dovich approximation in the quasinonlinear regime. On the other hand, for SCDM and LCDM models, the improvement by including the effect of the velocity dispersion was small.