A POSSIBLE LOCAL COUNTERPART TO THE EXCESS POPULATION OF FAINT BLUE GALAXIES

OBSERVATIONS have revealed a population of faint blue galaxies1-5 at i ntermediate redshifts (z almost-equal-to 0.4). These galaxies are pres ent in significant excess relative to what is expected based on observ ations of local galaxies, which has led some to propose that the discr epancy must be due either to non-standard cosmologies4,6 or to the eff ects of very pronounced galaxy evolution4,7-10. The surveys that defin e the population of local galaxies are strongly biased against objects of low surface brightness11-14. Recent work15,16 has shown that nearb y low-surface-brightness galaxies have properties very similar to thos e of the excess faint blue galaxies, and has suggested that they may b e as common as normal spiral galaxies14,17. Here I show that the deep surveys that have identified the faint blue galaxies can easily detect low-surface-brightness galaxies at intermediate redshifts, even thoug h they are not readily apparent in local surveys. Thus, the faint blue galaxies may indeed correspond to low-surface-brightness galaxies.