暗蓝星系计数的过剩问题

人们在极暗蓝星等处观测到数目巨大的星系，远比星系的无演化模型预计的多。随后的观测和理论发展进一步丰富了对暗蓝星系过剩问题的研究。Ｂ，Ｋ波段的星等计数、红移计数、颜色计数、成闭性等的观测是这一问题的主要观测约束。

The Problem of the Excess of Faint Blue Galactic Counts

The number of galaxies detected at faint blue magnitudes is much larger than predicted by no evolution model of galaxies.Both observational and theoretical work that followed have enriched the study of the excess of faint blue galaxies.Major observational constraints are B and K band galactic mumber counts;redshift and color distribution;and clustering of galaxies.Although the pure luminosity evolution model can account for the excess, the theory predicts too large a redshift distribution and requires a nonstandard cosmology, while a flat cosmology dominated by A or an open universe is inconflict with K band observations. Thus the number evolution of galaxies is a necessary element, either the merging model, or the additional population model which involves a new population of galaxies that once existed and disappeared afterwards, or a new noevolution model which has added low-surface-density galaxies at the faint end of nearby luminosity function. Nevertheless, the conclusion from the study of faint blue galaxies is still very vague, although it is generally believed that the blue dwarfs cause the excess.