Density field in extended Lagrangian perturbation theory
Abstract
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 selfgravitating fluid with pressure, given by a polytropic equation of state, using a perturbation method. Then we obtained the firstorder solutions in generic background universes and the secondorder solutions for a wider range of polytrope exponents. Using these results, we describe density fields with a scalefree spectrum, SCDM, and LCDM models. Then we analyze the crosscorrelation coefficient of the density field between Nbody simulation and Lagrangian linear perturbation theory, and the probability distribution of the density fluctuations. From our analyses, for scalefree 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.
 Publication:

Physical Review D
 Pub Date:
 April 2004
 DOI:
 10.1103/PhysRevD.69.084020
 arXiv:
 arXiv:astroph/0310825
 Bibcode:
 2004PhRvD..69h4020T
 Keywords:

 04.25.Nx;
 95.30.Lz;
 98.65.Dx;
 PostNewtonian approximation;
 perturbation theory;
 related approximations;
 Hydrodynamics;
 Superclusters;
 largescale structure of the Universe;
 Astrophysics
 EPrint:
 23 pages, 9 figures