Abstract
ABSTRACT Collisionless particles with masses ⪉100 eV ("massive neutrinos") would play a substantial role in the early development of density inhomogeneities in the expanding universe. Detailed calculations of 3- and 1-dimensional processes in an initially-slightly inhomogeneous cosmology show 3-d structure similar to the voids/pancake/string nature of the observations of large clusters of galaxies, and 1-d consistency with galaxy formation in neutrino-initiated pancake collapse. The 1-dimensional calculations apparently require a large baryon fraction ≡90% in hot intergalactic gas, in models which are essentially closed by massive neutrinos, and contain baryons at ≡0.1 closure density. These models are consistent, but 'delicately' so, with observations. Condensations based on heavier stable particles (m ⪆ 1 keV) would have typically galaxy - or smaller - sizes. They appear to be excluded because the cluster-of-galaxies correlation function is very much larger than that observed for galaxies. It is difficult to see how this result can be obtained by a dynamical clustering process, as would be required if collapses were initiated on galactic scales by heavy stable collisionless particles.
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