A CCD study of the environment of Seyfert galaxies. III. Host galaxies andthe nearby environments

A technique is described that permits the robust decomposition of the bulge and disk components of a sample of Seyfert galaxies, as well as a (control ) sample of nonactive galaxies matched to the Seyferts in the distributions of redshift, luminosity, and morphological classification. The structural parameters of the host galaxies in both samples are measured. No statistica lly significant differences at greater than the 95% level are found in thes e parameters according to a Kolmogorov-Smirnov test. "Companion galaxies"-d efined as any galaxy within a projected separation of 200 h(-1) kpc from th e center of the host-are identified and their basic properties measured. A comparison between the active and control samples in the distributions of a pparent R magnitude, absolute R magnitude (assuming the companions are at t he distance of the host), projected separation from the host, position angl e relative to the host, magnitude difference between the companion and host , and strength of the tidal parameter shows no statistically significant di fferences. Similarly, no statistically significant differences are found be tween the control and active sample host galaxies in terms of light asymmet ries-bars, rings, isophotal twisting, etc. The implications for a model in which interactions and mergers are responsible for inciting activity in gal actic nuclei are discussed briefly.