Global Properties of Multiple Merger Remnants

Merger remnants of small groups of galaxies are contrasted with relics ofmergers of pairs of galaxies to determine which process produces objects thatbest compare to real ellipticals. In both cases, the progenitors consist ofself-gravitating disks, halos, and, sometimes, bulges. Pairs of galaxies mergefrom orbits that initially have zero--energy. The systems that produce multiplemerger remnants are dense, six--member groups in virial equilibrium with lowvelocity dispersions. Multiple and pair mergers produce remnants which differin both their spatial and kinematic properties. Multiple merger remnants havesmall triaxialities and are most likely to appear nearly round from mostviewing angles. They possess cores, with sizes of a few tenths of an effectiveradius, that are more extended than pair remnant cores, even when bulges areincluded in the progenitors. In multiple mergers, the spin of all components --halo, disk, and bulge -- increases and, while velocity dispersion dominates inthe central regions, $v_r/\sigma \approx 1$ outside an effective radius in someprojections. The angular momentum and minor axis vectors are aligned formultiple merger remnants. During merging of multiple progenitors, about half ofthe orbital angular momentum in each luminous component is converted intointernal rotation in that component. Material is prevented from accumulating inthe center of multiple merger remnants as efficiently as it does in pairmergers. In pair mergers that include gas, unrealistically steep surfacebrightness profiles have been produced in center of the remnants; in multiplemergers the formation of overdense nuclei may be impeded, thus allowing moresuccessful comparison with real elliptical galaxies.Comment: 43 pages of uuencoded compressed postscript with 17 figures. Postscript figures 1,2,3,17, 3Mb total, available upon request from weil@ucolick.org. Accepted to the Astrophysical Journa