Canada‐France Redshift Survey. XIV. Spectral Properties of Field Galaxies up toz= 1

The spectral properties of more than 400 CFRS galaxies and their changes overthe redshift interval 0 - 1.3 are investigated. Emission line intensities andequivalent widths for accessible lines have been measured, as well as continuumcolor indices based on 200A wide spectral regions. Within the CFRS sample, thecomoving fraction of galaxies with significant emission lines (EW(OII) > 15A)increases from ~13% locally to over 50% at z > 0.5. The fraction of luminous (M_{B} < -20) quiescent galaxies (those without [OII] 3727 emission) decreaseswith redshift from 53% at z = 0.3 to 23% at z > 0.5, the latter fraction beingsimilar to that of early type galaxies at that redshift. There is considerableevidence in the data presented here that star formation increases from z = 0 toz > 0.5 in disk galaxies. However, the absence of extremely blue colors and thepresence of significant Balmer absorption suggests that the star formation isprimarily taking place over long periods of time, rather than inshort-duration, high-amplitude ``bursts''. There are several indications thatthe average metallicity and dust opacity were lower in emission-line galaxiesat high redshift than those typically seen in luminous galaxies locally. Beyondz = 0.7, almost all the emission-line galaxies, including the most luminous (at1mu at rest) ones, have colors approaching those of present-day irregulargalaxies, and a third of them have indications (primarily from the strength ofthe 4000A break) of metallicities significantly less than solar (Z < 0.2Z_{sun}). (abbreviated)