CANADA-FRANCE REDSHIFT SURVEY .14. SPECTRAL PROPERTIES OF FIELD GALAXIES UP TO Z=1

The spectral properties of more than 400 Canada-France Redshift Survey (CFRS) galaxies and their changes over the redshift interval 0 less t han or equal to z less than or equal to 1.3 are investigated. Emission -line intensities and equivalent widths for accessible lines have been measured as well as continuum color indices based on 200 Angstrom wid e spectral regions. Within the CFRS sample, the comoving fraction of g alaxies with significant emission lines [W-0(O II)> 15 Angstrom] incre ases from about 13% locally to over 50% at z > 0.5. The fraction of lu minous (M-B < -20) quiescent galaxies (those without [O II] 3727 emiss ion) decreases with redshift from 53% at z = 0.3 to 23% at z > 0.5, th e latter fraction being similar to that of early-type galaxies at that redshift. There is considerable evidence in the data presented here t hat star formation increases from z = O to z > 0.5 in disk galaxies. H owever, the absence of extremely blue colors and the presence of signi ficant Balmer absorption suggests that the star formation is primarily taking place over long periods of time, rather than in short-duration , high-amplitude '' bursts.'' There are several indications that the a verage metallicity and dust opacity were lower in emission-line galaxi es at high redshift than those typically seen in luminous galaxies loc ally. Beyond z = 0.7, almost all the emission-line galaxies, including the most luminous (at 1 mu m at rest) ones, have colors approaching t hose of present-day irregular galaxies, and one-third of them have ind ications (primarily from the strength of the 4000 Angstrom break) of m etallicities significantly less than solar (Z < 0.2 Z.) It is argued t hat changes in metallicity and dust extinction could be contributing t o the observed evolution of the line and continuum luminosity densitie s, the luminosity function, and/or the surface brightnesses and morpho logies of galaxies in the CFRS. If the Kennicutt (1992) relation is us ed to convert the large increase in the comoving luminosity density of [O II] 3727 back to z similar to 1 into a star formation rate, then i t implies a present stellar mass density in excess of that observed lo cally. This result suggests that the Kennicutt relation is inappropria te for the CFRS objects, perhaps because of the changes in their metal licities and dust opacities and/or in their initial mass functions. Us ing the Gallagher et al. (1989) relation for objects having colors of irregular galaxies reduces the production of long-lived stars since z = 1 to 75% of the present-day value. More complex mechanisms are proba bly responsible for changes seen in the emission-line ratios of H II r egions in CFRS galaxies, which show higher ionization parameters than local H II galaxy ones. This change could be due to a higher ionizing efficiency of the photons from hot stars in galaxies at high redshift.