EMISSION-LINE GALAXIES IN THE SLICE OF THE UNIVERSE .2. THE DEEP CASE SURVEY SAMPLE

We present an analysis of the spatial distribution for a complete sample of galaxies cataloged in the first two lists of the Case Low-Dispersion Northern Sky Survey. This sample of 176 objects was selected for detailed follow-up investigation because it is located in fields which overlap the original Slice of the Universe survey of de Lapparent et al. We utilize the depth of the redshift sample of normal galaxies in this field to study the relative spatial distributions of the Case and SLICE galaxies. In this study we (i) investigate the role that galaxy-galaxy encounters might play in triggering star formation; (ii) assess the utility of using emission-line/UV-excess selected galaxies to map out large-scale structures at high redshift; (iii) look for evidence of biasing in the spatial distribution of low-luminosity galaxies, which are more readily detected in objective-prism surveys than in magnitude-limited surveys. We conclude that galaxy-galaxy encounters are not the primary cause of star formation in the majority of the Case galaxies which tend to be more, not less, isolated than their nonactive counterparts. This higher level of isolation is consistent with biasing in the spatial distribution of low-luminosity galaxies but is subtle enough that emission-line galaxies can be used as effective tracers of the large-scale clustering of field galaxies.