Abstract
DEEP sky surveys have turned up unexpectedly large numbers of faint blue galaxies1,2—three to five times more than would be estimated by extrapolation from the present galaxy population assuming no evolution. Unless distances to these faint galaxies are known, it is difficult to distinguish between luminosity evolution (in which case, galaxies in the past were systematically brighter) and density evolution (as, for example, if modern galaxies are the results of mergers of earlier ones). We have obtained redshifts and K magnitudes for a small but complete sample of 22 galaxies with B magnitude down to 24. In the luminosity range B = 23–24, the B-band galaxy counts are dominated by a population of small blue galaxies at z ≈ ~ 0.25, which may collectively contain as much baryonic matter as the normal galaxies. It is possible either that these earlier galaxies have undergone merging3 to create the present galaxy population, or that they represent a quite different galactic population which has now faded or disappeared4. Either possibility has considerable implications for our understanding of galaxy formation.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
