A Study of the Emission Line Properties of Faint Field Galaxies
Session 61 -- Properties and Evolution of Clusters of Galaxies
Display presentation, Thursday, 2, 1994, 9:20-6:30

## [61.13] A Study of the Emission Line Properties of Faint Field Galaxies

C. Gronwall, D.C. Koo (UC Santa Cruz and UCO/Lick)

Measurements of the equivalent width (EW) of [OII]$\lambda$3727 line in faint field galaxies have been used by some workers to claim that there is an increase in star-formation activity at z $\geq 0.1$ which can only be explained by galaxies with short-lived bursts of star formation. Others maintain that there is currently no evidence for an increase in [OII] EW with redshift due to uncertainties in the local comparison samples and to a possible correlation of EW with absolute magnitude, such that low luminosity galaxies have larger EWs.

We will present preliminary results based on the inclusion of nebular emission into the models of spectrophotometric evolution models of Bruzual \& Charlot (1993, ApJ 405, 538). Kennicutt (1992, ApJ, 388, 310) has shown that there is a strong correlation between [OII] and H$\alpha$ EWs. Thus, given the known star formation rates of our spectrophotometric evolution models as a function of time, we can calculate predicted [OII] EWs versus redshift, apparent magnitude, or color for galaxies with varying star formation histories. Incorporating such knowledge into our currently existing non-negative least squares fitting routines (Koo, Gronwall, \& Bruzual 1993, ApJ, 415, L21), we will compute whether bursts of star formation are necessary to explain the observed [OII] EWs as well as the counts, colors, and redshifts of faint field galaxies.