标题： 星团矮星的演化 显示英文标题

标题： The evolution of cluster dwarfs

摘要： 我们总结了利用哈勃空间望远镜高级巡天相机观测的六个红移 0.14 < z < 0.40 的星系团的结果。我们得到了在 B、g、V、r、i 和 z 波段的深组合光度函数，绝对星等达到 -14 +5 log h mag。这些光度函数用单个 Schechter 函数拟合，其对应的 M^* 值分别为 -19.8、-20.9、-21.9、-22.0、-21.7 和 -22.3（对应 B、g、V、r、i、z 波段），并且所有波段的 α 值均为 -1.3。数据表明，红色序列主导着光度函数，在 L* 以下超过 6 个星等，进入矮椭球星系区域。因此，至少在 z=0.3 时，红色序列已经很好地建立，并且这些星团中的矮椭球星系已完全形成。我们没有探测到低红移星团中观测到的暗端上升（M > -16）。如果这是真实的，那么暗端星族是在 z=0.3 之后形成的。 显示英文摘要

摘要： We summarize the results from analyzing six clusters of galaxies at 0.14 < z < 0.40 observed with the Hubble Space Telescope Advanced Camera for Surveys. We derive deep composite luminosity functions in B,g,V,r,i and z down to an absolute magnitude of -14 +5 log h mag. The luminosity functions are fitted by a single Schechter function with M^*=-19.8,-20.9,-21.9, -22.0,-21.7 and -22.3 i B,g,V.r,i,z respectively and alpha=-1.3 for all bands. The data suggest that the red sequence dominates the luminosity function down to more than 6 mag. below L*, the dwarf spheroidal regime. Hence, at least at z=0.3 the red sequence is well established and galaxies down to dwarf spheroidals are fully assembled within these clusters. We do not detect the faint-end upturn (M > -16) that is observed in lower redshift clusters. If this is real, the faint-end population has originated since z = 0.3.