Galaxy Evolution in a Pilot Survey up toz=1and CDM Halos

We study spectral evolution of galaxies in a magnitude limited sample of 550galaxies from z=1 down to z=0.3 on a pencil beam of≈10′×10′.We concentrate on the large apparent cosmological structures along the line ofsight, and we bin our individual galaxy spectra to obtain representative highS/N spectra based upon these structures. We divide the resulting averagespectra in three groups to facilitate the analysis:galaxies with pureabsorption line spectra, galaxies with emission lines and blue continua, andgalaxies with emission lines and red continua.We revisit the question of downsizing in emission-line galaxies betweenz=0.9 and z=0.45 in our pencil-beam and find the following results:strong star formation in emission line galaxies, aging in emission linegalaxies, and aging in absorption systems, are shifting from bright to faintsystems as cosmological time increases. Each redshift bin is repopulated innew starbursts.Therefore at redshifts z⩽1 galaxy formation is downsizing both inluminosity and number density. Our observations indicate that at z⩽1star formation and hierarchical structure formation of CDM halos are not inphase