AAS 198th Meeting, June 2001
Session 36. Interacting Galaxies
Display, Tuesday, June 5, 2001, 10:00am-6:30pm, Exhibit Hall

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[36.01] The Frequency of Active and Normal Galaxies with Companions

H. R. Schmitt (NRAO-Socorro)

One of the major concerns in the study of AGN's is the mechanisms for fueling the nucleus, for moving gas from galactic scales down to the inner ~1 pc region of the galaxy. It was proposed that one possible mechanism could be the interaction between galaxies, which can funnel gas into the nucleus. Several papers have searched for an excess of Seyfert galaxies with companions; however, there is no consensus in this subject, with results depending on the way the sample and control sample are selected. Here we present the result of a search for companion galaxies around the Palomar sample galaxies (Ho et al. 1997). This sample is ideal for such a study, because it includes all galaxies with B<12.5 mag in the northern hemisphere, with homogeneous activity classification of all the galaxies. Our technique is to consider that two galaxies are companions if their distances are smaller than 5 times the diameter of the galaxy, their radial velocities differ by less than 1000 km s-1 and their brightnesses by less than 3 magnitudes. We find that there is a significantly larger percentage of LINER's, Transition galaxies and absorption line galaxies with companions than Seyferts and HII galaxies. This result changes depending on how the sample is divided. For example, if we consider only galaxies with morphological types later than Sa, we find that there is no significant difference in the percentage of companions of all galaxy types. We will discuss the results of these and other tests, as well as their implications. NRAO is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities Inc.

The author(s) of this abstract have provided an email address for comments about the abstract: hschmitt@aoc.nrao.edu

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