Galaxy Mergers - Galaxy Mergers Dynamical models show that...

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Galaxy Mergers Dynamical models show that galaxies are very sticky, and that a deeply penetrating encounter can dissipate so much orbital energy that a coalescence is inevitable. Simple estimates suggest that most bright galaxies must have undergone at least one merger of near-equals (see Toomre 1977, Yale conference p. 401); there have been many numerical studies of what happens here, so we have a good idea of what to look for in the real universe. In fact, there are several useful relics of mergers. Most commonly sought are tidal tails from a single main body; the dynamical evolution of the core proceeds so fast that tails from initial disks will still be visible for several billion years after the nuclei have merged. F. Schweizer 1982 (ApJ 252, 455) has shown that this in the case in NGC 7252, with a central body approaching a de Vaucouleurs light distribution while counter-rotating motions and tidal tails still exist farther out. Numerous such merger candidates have been identified from optical imaging; many are also strong IR sources. These have some of the most strongly enhanced far-IR levels observed, extending the notion of enhanced star formation to the most violent interactions possible; there has been some discussion
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This note was uploaded on 11/10/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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Galaxy Mergers - Galaxy Mergers Dynamical models show that...

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