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

OBSERVATIONS have revealed a population of faint blue galaxies1-5 at intermediate redshifts (z almost-equal-to 0.4). These galaxies are present in significant excess relative to what is expected based on observations of local galaxies, which has led some to propose that the discrepancy must be due either to non-standard cosmologies4,6 or to the effects of very pronounced galaxy evolution4,7-10. The surveys that define the population of local galaxies are strongly biased against objects of low surface brightness11-14. Recent work15,16 has shown that nearby low-surface-brightness galaxies have properties very similar to those of the excess faint blue galaxies, and has suggested that they may be 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 though they are not readily apparent in local surveys. Thus, the faint blue galaxies may indeed correspond to low-surface-brightness galaxies.