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Paper: The evolution of field galaxies - Is Omega = 1?
Volume: 10, Evolution of the Universe of Galaxies: Edwin Hubble Centennial Symposium
Page: 268
Authors: Koo, David C.
Abstract: Recent optical observations of the counts, colors, and redshifts of very faint field galaxies have forced a major turning point in the study of the evolution of faint galaxies. In particular, independent counts of faint galaxies are so high that low density (low Omega) universes are strongly favored with reasonable models of the luminosity evolution of distant galaxies. Arguments are made that the bulk of the faint galaxies are not due to extremely low-luminosity dwarf galaxies, despite the relatively poor knowledge of their local number density. The major conclusion is that a high density (Omega = 1) Friedmann universe can be salvaged only if the assumption of the conservation of comoving volume number density of galaxies is droped, presumably because of significant merging of luminous galaxies at high redshifts. The effects on number counts and redshift distributions of several simple parametric descriptions of the evolution of number density, luminosity, and shape of the faint end of the luminosity function are explored.
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