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Paper: Evolution of the 3.6μm Cluster Luminosity Function
Volume: 357, The Spitzer Space Telescope: New Views of the Cosmos
Page: 246
Authors: Muzzin, A.; Wilson, G.; Lacy, M.
Abstract: We have measured the 3.6μm cluster luminosity function (LF) using a sample of 123 galaxy clusters selected from the 4 degree2 Spitzer First Look Survey (FLS). The clusters were selected on the basis of their R - 3.6μm colors using the cluster red-sequence technique of Gladders & Yee (2000). The binned LFs are well-fit by a Schechter function at all redshifts. However, we note two interesting trends. Firstly, the evolution of M* with redshift is consistent with models that form galaxies in a single-burst of star-formation at z > 2.0, and evolve passively thereafter. Secondly, the faint-end slope of the LF appears to become shallower at higher redshift. We conclude that the most massive galaxies were formed in the cluster at high redshift (z > 2.), while lower-mass galaxies have subsequently been accreted from the field at lower redshift (z ∼ 0.5). These results are consistent with the “downsizing” picture seen in previous cluster studies using smaller samples.
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