Formation and evolution of E plus A galaxies in dusty starburst galaxies

The formation and evolution of the "E+A" (also named "k+a" and "a+k" types by A. Dressler et al.) galaxies found in significant numbers in the cores o f intermediate-redshift clusters has been extensively discussed by many aut hors. In this Letter, we model the spectral, dynamical, and morphological e volution of a prime candidate for producing this spectral signature: a dust y starburst associated with a major galaxy merger. We show that as this sys tem evolves dynamically, its spectral type changes from an "e(a)" type (exh ibiting strong Hd absorption and modest [O II] emission-the identifying fea tures of local dusty starburst galaxies) to a k+a type and then finally to a passive "k" type. This result shows that galaxies with an e(a) spectral t ype can be precursors to the k+a systems and that dynamical evolution great ly controls the spectral evolution in these merger cases. Our simulations a lso show that a merger with very high infrared luminosity (L-IR > 10(11) L. ) is more likely to show an e(a) spectrum, which implies that spectral type s can be correlated with infrared fluxes in dusty starburst galaxies. With these results, we discuss the origin of the evolution of k+a/a+k galaxies i n distant clusters and the role merging is likely to have.