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E. J. Barton (CfA), B. C. Bromley (Physics Dept., University of Utah), M. J. Geller (CfA)
We use self-consistent N-body models, in conjunction with models of test particles moving in galaxy potentials, to explore the initial effects of interactions on the rotation curves of spiral galaxies. Using nearly self-consistent disk/bulge/halo galaxy models (Kuijken and Dubinski 1995), we simulate the first pass of galaxies on initially parabolic orbits with varying impact parameters, orbit inclinations and galaxy halo masses. For each simulation, we mimic observed ``rotation curves'' of the model galaxies. Interaction-induced features of the curves include distinctly rising or falling profiles at large radii and pronounced bumps in the central regions.
The simulations provide a possible physical basis for remarkably similar features which appear in our sample of ~140 emission line rotation curves of paired spiral and S0 galaxies; our study also includes B and R images of the pairs and nuclear spectra. The galaxies are a subsample of the complete set of 791 galaxies in pairs and n-tuples with projected separations \leq 50 {\rm\ h-1\ kpc} and velocity separations \leq 1000 {\rm\ km\ s-1} in the CfA2 redshift survey. The size and relative completeness of the sample allow modeling of selection effects and detailed statistical comparison to our models and existing simulations of interacting galaxies. The study will provide constraints on the frequency of interaction features, the orbits and the dark matter composition of galaxy pairs and n-tuples in our sample.