Color and Morphology of Galaxies in the Region of the 3C 324 Clusters at z ~ 1.2

Abstract

We investigated the color and morphology of optically selected galaxies in the region of clusters at z ~ 1.2 near to the radio galaxy 3C 324 using archived data taken with the Hubble Space Telescope. The faint galaxies selected at the HST F702W band that contribute to the surface-density excess of the region have wide ranges of color, size, and morphology, which are not likely to be due to contamination by foreground galaxies. Namely, the rest-frame ultraviolet emission properties of the galaxies in the clusters are not very homogeneous; various amounts of star-formation activity may occur in a significant fraction of them. Although our analysis is purely statistical, we find that typical star-forming galaxies with blue colors have a relatively late-type morphology compared to the red quiescent population in the systems.