THE FAINT END OF THE GALAXY LUMINOSITY FUNCTION IN A1689: A STEEP RED FAINT END UPTURN AT <i>z</i>=0.18
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2010
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Abstract
We present a deep and wide I luminosity function (LF) for galaxies in A1689 (z = 0.183) from a mosaic of Hubble Space Telescope WFPC2 images covering 10' on the side. The main result of this work is the detection of a steep upturn in the dwarf galaxy LF, with alpha similar to-2. The dwarf-to-giant ratio appears to increase outward, but this is because giant galaxies are missing in the cluster outskirts, indicating luminosity segregation. The red sequence LF has the same parameters, within errors, as the total LF, showing that the faint end upturn consists of red quiescent galaxies. We speculate that the upturn is connected to the "filling-in" of the red sequence at z < 0.4 and may represent the latest installment of "downsizing" as the least massive galaxies are being quenched at the present epoch.
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galaxies: clusters: individual (A1689), galaxies: dwarf, galaxies: luminosity function, mass function