The Rest-frame H-band Luminosity Function of Red-sequence Galaxies in Clusters at 1.0 < z < 1.3

Abstract

We present results on the rest-frame H-band luminosity functions (LFs) of red-sequence galaxies in seven clusters at 1.0 < z < 1.3 from the Gemini Observations of Galaxies in Rich Early Environments Survey. Using deep GMOS z<SUP>\prime</SUP> and IRAC 3.6 μm imaging, we identify red-sequence galaxies and measure their LFs down to {M}<SUB>H</SUB>∼ {M}<SUB>H</SUB><SUP>* </SUP>+(2.0-3.0). By stacking the entire sample, we derive a shallow faint-end slope of α ∼ -{0.35}<SUB>-0.15</SUB><SUP>+0.15</SUP> and {M}<SUB>H</SUB><SUP>* </SUP>∼ -{23.52}<SUB>-0.17</SUB><SUP>+0.15</SUP>, suggesting that there is a deficit of faint red-sequence galaxies in clusters at high redshift. By comparing the stacked red-sequence LF of our sample with a sample of clusters at z ∼ 0.6, we find an evolution of the faint end of the red sequence over the ∼2.6 Gyr between the two samples, with the mean faint-end red-sequence luminosity growing by more than a factor of 2. The faint-to-luminous ratio of our sample ({0.78}<SUB>-0.15</SUB><SUP>+0.19</SUP>) is consistent with the trend of decreasing ratio with increasing redshift proposed in previous studies. A comparison with the field shows that the faint-to-luminous ratios in clusters are consistent with those in the field at z ∼ 1.15 and exhibit a stronger redshift dependence. Our results support the picture that the buildup of faint red-sequence galaxies occurs gradually over time and suggest that faint cluster galaxies, similar to bright cluster galaxies, already experience the quenching effect induced by the environment at z ∼ 1.15.