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The Canada-France Redshift Survey XII: Nature of emission-line field galaxy population up to z = 0.3

L. Tresse·C. Rola·F. Hammer·G. Stasinska·O. Le Fevre·S. J. Lilly·D. Crampton
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Abstract

We present a spectroscopic study of the 138 field galaxies to a redshift z = 0.3 from the I-selected Canada-France Redshift Survey. 117(85%) spectra exhibit at least H alpha in emission, the remaining 21(15%) are purely absorption-line spectra. We focus our analysis on spectra with H alpha and H beta in emission, accounting for about half of this low-z sample, which we classify using emission-line ratio diagrams. Using photoionization models, we determine the extreme boundaries of H II galaxies in these diagnostic diagrams, and demonstrate that the emission-line ratios of a significant fraction of galaxies require harder photoionization sources than massive O stars. We find that about 17% of the field galaxies have emission-line ratios consistent with active galaxies, e.g., Seyfert 2 or LINERs. After correcting for stellar absorption under the Balmer lines, we conclude that the fraction of such galaxies is at least 8% of the field galaxy population at z < 0.3.

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L. Tresse, C. Rola, F. Hammer, G. Stasinska, O. Le Fevre, S. J. Lilly, D. Crampton. 1996-04-04. The Canada-France Redshift Survey XII: Nature of emission-line field galaxy population up to z = 0.3. https://doi.org/10.1093/mnras%2F281.3.847

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