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Paper: Spectroscopy of large numbers of faint galaxies
Volume: 10, Evolution of the Universe of Galaxies: Edwin Hubble Centennial Symposium
Page: 248
Authors: Ellis, Richard S.
Abstract: Multiple object spectroscopy with high throughput spectrographs at last makes it possible to directly address the origin of the excess faint galaxies seen in the classical number magnitude count studies. Data from two AAT deep spectroscopic surveys show no obvious departures from a no-evolution redshift distribution. Important questions of statistical completeness and clustering are discussed. The results cannot easily be reconciled with models invoking strong luminosity evolution to explain the excess population. Neither are the results compatible with a hitherto undiscovered population of local dwarfs. Evolution must be mostly confined to low luminosity objects undergoing short-term star-formation activity which increases in strength or frequency with look-back time. Together with the existence of early-type objects with present-day colors to much higher redshifts, such activity at recent times provides important evidence for two-tier models of galaxy formation.
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