A CCD study of the environment of Seyfert galaxies. III. Host galaxies and the 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 statistically significant differences at greater than the 95% level are found in these parameters according to a Kolmogorov-Smirnov test. Companion galaxies-defined as any galaxy within a projected separation of 200 h(-1) kpc from the center of the host-are identified and their basic properties measured. A comparison between the active and control samples in the distributions of apparent R magnitude, absolute R magnitude (assuming the companions are at the distance of the host), projected separation from the host, position angle relative to the host, magnitude difference between the companion and host, and strength of the tidal parameter shows no statistically significant differences. Similarly, no statistically significant differences are found between the control and active sample host galaxies in terms of light asymmetries-bars, rings, isophotal twisting, etc. The implications for a model in which interactions and mergers are responsible for inciting activity in galactic nuclei are discussed briefly.