ABSTRACT

We are studying the optical, radio, and X-ray morphologies of interacting galaxies in which at least one member is also an active galaxy. Deformed gas distributions are seen in galaxies that also show optical evidence of tidal deformation, indicating significant gas redistribution in these interacting systems, thereby providing compelling evidence for a causal connection between tidal and nuclear activity in “interactive” galaxies.

THE INTERACTION-ACTIVITY CONNECTION

Stockton (1990) and Heckman (1990) have reviewed the wealth of evidence indicating that galaxy interactions are somehow related to the generation of starburst and AGN activity in galactic nuclei. For example, a large fraction of low-luminosity radio and active galaxies have nearby companions or show evidence for a recent gravitational encounter (e.g., MacKenty 1989). In an optical study of galaxies selected on the basis that they all contain well defined radio jets, it was found that almost half of the sample consists of pairs of elliptical galaxies (Colina and Pérez-Fournon 1990a, b). Many of these low-luminosity radio galaxies with companions (e.g., 3C31, 3C278, and 3C449) show a well defined distorted radio jet structure at the VLA scale with an S– or C-shaped morphology. We are currently studying these systems across many wavebands (optical, radio, and X-ray) in an attempt to model the observed morphologies in each case and thereby constrain the various properties of the system (orbital parameters, jet parameters, and hot gas distribution, respectively). These system constraints will hopefully offer some physical insight into the interaction-activity connection.