We report a systematic multi-wavelength investigation of environments of the brightest cluster galaxies ( BCGs ) , using the X-ray data from the Chandra archive , and optical images taken with 34 ’ \times 27 ’ field-of-view Subaru Suprime-Cam .
Our goal is to help understand the relationship between the BCGs and their host clusters , and between the BCGs and other galaxies , to eventually address a question of the formation and co-evolution of BCGs and the clusters .

Our results include : 1 ) Morphological variety of BCGs , or the second or the third brightest galaxy ( BCG2 , BCG3 ) , is comparable to that of other bright red sequence galaxies , suggesting that we have a continuous variation of morphology between BCGs , BCG2 , and BCG3 , rather than a sharp separation between the BCG and the rest of the bright galaxies .
2 ) The offset of the BCG position relative to the cluster centre is correlated to the degree of concentration of cluster X-ray morphology ( Spearman \rho = -0.79 ) , consistent with an interpretation that BCGs tend to be off-centered inside dynamically unsettled clusters .
3 ) Morphologically disturbed clusters tend to harbour the brighter BCGs , implying that the “ early collapse ” may not be the only major mechanism to control the BCG formation and evolution .