Astronomy and Astrophysics – Astrophysics
Scientific paper
Aug 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994apj...431..477b&link_type=abstract
The Astrophysical Journal, vol. 431, no. 2, pt. 1, p. 477-485
Astronomy and Astrophysics
Astrophysics
34
Dark Matter, Galactic Clusters, Galactic Evolution, Galactic Mass, Halos, Computerized Simulation, Cosmology, Data Correlation, Many Body Problem, Red Shift
Scientific paper
Using a large N-body simulation, we investigate the evolution of clustering of mass particles and individual dark matter halos in a standard cold dark matter (CDM) universe. The two-point correlation function, zeta(r), is computed at several epochs in the simulation corresponding the redshifts, z, between 5 and 0, where z = 0 corresponds to a bias parameter, b, of 1. Previous studies of the evolution of clustering in CDM universes have investigated a much smaller range of redshifts. Two classes of halos are considered: high overdensity (approximately 2000) and moderate overdensity (approximately 250). The evolution of zeta(r) as a function of halo mass is also investigated. The two-point correlation function evloves differently from the prediction of linear theory, both in the case of the mass particles and the individual halos. The amplitude of zeta(r) for the mass grows continuously over the course of the simulation, but from z = 1.5 to z = 0, it grows more slowly than linear theory on large scales (r approximately 9h-1 Mpc). The two-point correlation functions of various catalogs of halos exhibit evolution that is strikingly different from linear theory. The details of the evolution of zeta(r) for the halos are a function of both the overdensity and mass of the halos, but four general patterns emerge: (1) a decrease in the amplitude of zeta(r) from z = 5 to z approximately 2, followed by an increase in the amplitude of zeta(r) from z approximately equal 2 to z = 0 (small, moderate-overdensity halos), (2) a decrease in the amplitude of zeta(r) from z = 5 to z approximately equal 1, after which the amplitude of zeta(r) remains approximately constant (large, moderate-overdensity halos), (3) little evolution from z = 5 to z approximately equal 1, followed by obvious small-scale evolution from z approximately equal 1 to z approximately equal 0 (small, high-overdensity halos), and (4) no noticeable evolution in zeta(r) over the course of the simulation (large, high-overdensity halos). Each catalog of halos is strongly clustered at early epochs in the simulation, implying that if the universe is dominated by CDM and b approximately equal 1 today, high-redshift galaxies should be strongly clustered. The redshift at which the observed galaxy correlation amplitude is at a minimum can be used to infer the current value of b.
Brainerd Tereasa G.
Villumsen Jens V.
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