Features of high redshift galaxies and their environment

Abstract

In the framework of biased cold dark matter scheme (CDM model), assuming galaxies were formed at z ∼ 5, the virialization process of groups and clusters of galaxies was investigated. Because the amplitudes of primordial fluctuation at different scales are similar, when groups and clusters of galaxies virialize, the galaxies still have a rich interstellar gas and can be strongly affected by their environment. Galaxies will acquire high velocity and collide with each other during or after the virialization process, this may be the cause of activities in galaxies. High pressure cocoon formed by radio jets and the high ram pressure in the central region of a cluster of galaxies will expel the hot gas and squeeze the warm clouds in the interstellar medium, a starburst will follow, which can account for the Butcher-Oemler effect in clusters of galaxies and the radio-optical alignments of high redshift radio galaxies.