Evolution of velocity and density fields around clusters of galaxies

Abstract

The evolution of the averaged density and infall velocity profiles around clusters of galaxies is explored in several cosmological scenarios based on gravitational instability. The analysis is based on the statistics of peaks in random Gaussian fields and the spherical infall model. This method is shown to give accurate predictions of the cluster-galaxy cross-correlation function when compared with N-body simulations. The predictions for the average infall velocity as function of radius are not as accurate but are still useful. The predictions for the cluster-galaxy cross-correlation function on large scales are very different for models with little power on large scales (such as the cold dark matter and the hot dark matter models) and models with much power on large scales (such as primordial isocurvature baryon models). The ensemble average infall velocity as a function of radius provides a useful method for distinguishing between models with different levels of biasing of the galaxy number density fluctuations relative to mass fluctuations. 45 refs.