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Session 83 - Galaxy Evolution/Interaction.
Oral session, Wednesday, January 15
Piers 4/5,

[83.06] Near Parabolic Orbits in Relation to Merger Rates of Galaxies

T. K. Chatterjee, V. B. Magalinsky (FCFM, U. A. Puebla, Mexico)

The existence of physical galaxy pairs in near parabolic, marginally bound, orbits is supported strongly by recent observational evidence. A major dynamical implication of the existence of such pairs is that they will affect the rate of galaxy mergers explicitly and implicitly. We consider collisions which are on the verge of escape and lead to merger in an enormous timescale. A dynamical study of collisions, including ones on the verge of escape, on the galaxy merger rates is conducted and the galaxy merger rate is determined with respect to dense regions of the Universe; because mergers are observed predominantly in such regions (and as such the observational value is biased in favor of such regions). The implicit aspect is also considered; (that is in the case of rapture of a pair the probability of the components of the pair encountering another galaxy and the consequent probability of an ensuing merger). Results indicate that its is possible to almost reproduce the observed value of the merger rate s for the present epoch (to an order of magnitude). However if the relevant determinations are carried out with respect to regions of average and space densities, the expected value falls short of the observed value. As marginally bound collisions are the most frequent ones, their cumulative effect is likely to play a prominent part in imparting evolutionary trends to the fundamental plane.

Program listing for Wednesday