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

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 and IRAC 3.6 μm imaging, we identify red-sequence galaxies and measure their LFs down to M_H ^∗ ∼ M_H ^∗ + (2.0 - 3.0) . By stacking the entire sample, we derive a shallow faint-end slope of α ∼ -0.35_-0.15 ^+0.15 and M_H ^∗ ∼ -23.52_0.17 ^+0.15, 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_-0.15 ^+0.19) 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.