Pregalactic evolution in cosmologies with cold dark matter

Abstract

We discuss the possibility that the first objects forming in a universe dominated by cold dark matter might influence subsequent structure. We argue that the first objects would be stars forming in clusters of mass $$\sim10^5\enspace M_\odot$$ which have condensed from the high-σ overdensity peaks in the initial fluctuation spectrum. Two simple mechanisms – photoionization and supernovae – may cause feedback effects which can significantly perturb the subsequent evolution from a simple hierarchical clustering progression. We discuss the possibility that effects arising from these initial small-scale clusters might influence regions on galactic scales and suggest tentative ideas which may give clues to the biasing of galaxy formation necessary in an $$\Omega=1$$ universe.