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M. Kaufman (Ohio State U.), C. Struck (Iowa State U.), E. Brinks (U. Hertfordshire), M. Thomasson (Onsala Space Obs.), B. G. Elmegreen (IBM), D. M. Elmegreen (Vassar)
The galaxy pair NGC 2207/IC 2163 has an unusually high ratio of radio continuum/IRAS far-IR flux, yet neither galaxy contains an AGN. We present a 4.86 GHz radio continuum image of this pair from VLA observations with 2.5'' resolution. Much of the excess radio emission arises from apparent shock fronts in the outer parts of the companion sides of the galaxies and along the rim of the ocular oval of IC 2163. With a SFR deduced from H\alpha emission, each galaxy has a SFR/M(HI) typical of normal spiral disks. Unlike the radio continuum emission, the H\alpha emission is not enhanced on the companion side of NGC 2207. We also present the results of a detailed, hydrodynamic numerical simulation of the encounter, modelling the responses of the stars and gas in both galaxies in three dimensions. The short-lived ocular phase and other features, such as the HI kinematics, set strict constraints on the encounter model. In the model, shocks generated by disk scraping and mass transfer from IC 2163 to NGC 2207 occur and may account for the excess radio emission on the companion sides. Comparison with Spitzer observations of this pair will be made.
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.