The Fate of Cannibalized Fundamental‐Plane Elliptical Galaxies

Evolution and disruption of galaxies orbiting in the gravitational field of alarger cluster galaxy are driven by three coupled mechanisms: 1) the heatingdue to its time dependent motion in the primary; 2) mass loss due to the tidalstrain field; and 3) orbital decay. Previous work demonstrated that tidalheating is effective well inside the impulse approximation limit. Not only doesthe overall energy increase over previous predictions, but the work is donedeep inside the secondary galaxy, e.g. at or inside the half mass radius inmost cases. Here, these ideas applied to cannibalization of elliptical galaxieswith fundamental-plane parameters. In summary, satellites which can fall to thecenter of a cluster giant by dynamical friction are evaporated by internalheating by the time they reach the center. This suggests that truemerger-produced multiple nuclei giants should be rare. Specifically,secondaries with mass ratios as small as 1\% on any initial orbit evaporate andthose on eccentric orbits with mass ratios as small as 0.1\% evolvesignificantly and nearly evaporate in a galaxian age. Captured satellites withmass ratios smaller than roughly 1\% have insufficient time to decay to thecenter. After many accretion events, the model predicts that the merged systemhas a profile similar to that of the original primary with a weak increase inconcentration.Comment: 19 pages, 10 Postscript figures, uses aaspp4.sty. Submitted to Astrophysical Journa