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Paper: Modeling the Evolution of the Red Sequence through Mergers
Volume: 477, Galaxy Mergers in an Evolving Universe
Page: 119
Authors: Skelton, R. E.
Abstract: Mergers along the red sequence are thought to be important for building up the most massive early-type galaxies, yet these galaxies are often thought of as old and passively-evolving, having formed all their stars at high redshift. We use a simple toy model to explore the effects of varying star formation histories and mergers on the evolution of the red sequence population. We set up a reasonably realistic red sequence at z = 1 and show three illustrative scenarios for its evolution thereafter. With no further mergers or star formation, massive galaxies evolve very rapidly, overshooting the observed evolution. Dry mergers increase the mass of the galaxies, counteracting some of the luminosity evolution and leading to a distribution of galaxies that closely resembles the observed low-z population. If some galaxies continue to form stars and move onto the red sequence after undergoing a major gas-rich merger at z < 1, younger stellar populations are incorporated into red sequence galaxies, making them somewhat bluer and brighter. This further reduces the average change in color and magnitude for massive galaxies. The resultant luminosity evolution in this hierarchical model appears consistent with the passive evolution of an old population even though there has been significant growth in mass since z = 1.
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