Second-order power spectrum and nonlinear evolution at high redshift

Abstract

view Abstract Citations (243) References (39) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Second-Order Power Spectrum and Nonlinear Evolution at High Redshift Jain, Bhuvnesh ; Bertschinger, Edmund Abstract The Eulerian cosmological fluid equations are used to study the nonlinear mode coupling of density fluctuations. We evaluate the second-order power spectrum including all four-point contributions. In the weakly nonlinear regime we find that the dominant nonlinear contribution for realistic cosmological spectra is made by the coupling of long-wave modes and is well estimated by second order perturbation theory. For a linear spectrum like that of the cold dark matter model, second order effects cause a significant enhancement of the high $k$ part of the spectrum and a slight suppression at low $k$ near the peak of the spectrum. Our perturbative results agree well in the quasilinear regime with the nonlinear spectrum from high-resolution N-body simulations. We find that due to the long-wave mode coupling, characteristic nonlinear masses grow less slowly in time (i.e., are larger at higher redshifts) than would be estimated using the linear power spectrum. For the cold dark matter model at $(1+z)=(20,10,5,2)$ the nonlinear mass is about $(180,8,2.5,1.6)$ times (respectively) larger than a linear extrapolation would indicate, if the condition rms $\delta\rho/\rho =1$ is used to define the nonlinear scale. At high redshift the Press-Schechter mass distribution significantly underestimates the abundance of high-mass objects for the cold dark matter model. Although the quantitative results depend on the definition of the nonlinear scale, these basic consequences hold for any initial spectrum whose post-recombination spectral index $n$ decreases sufficiently rapidly with increasing $k$, a feature which arises quite generally during the transition from a radiation- to matter-dominated universe. Publication: The Astrophysical Journal Pub Date: August 1994 DOI: 10.1086/174502 arXiv: arXiv:astro-ph/9311070 Bibcode: 1994ApJ...431..495J Keywords: Dark Matter; Galactic Clusters; Galactic Evolution; Mass Distribution; Power Spectra; Red Shift; Astronomical Models; Cosmology; Coupling; Galactic Mass; Many Body Problem; Perturbation Theory; Relativity; Space Density; Space-Time Functions; Astrophysics; COSMOLOGY: THEORY; COSMOLOGY: LARGE-SCALE STRUCTURE OF UNIVERSE; GALAXIES: CLUSTERING; GALAXIES: FORMATION; Astrophysics E-Print: 25 pages, AAS Latex v3.0, figures and postscript available by anonymous ftp to arcturus.mit.edu, submittted to ApJ, preprint IAS-AST-93/70 and MIT-CSR-93-32 full text sources arXiv | ADS |