Substructures of Galaxy Cluster Abell 2537

Abell 2537 has been regarded as one of relaxed galaxy clusters because the X-ray emission is regular and symmetric, while there is also evidence to the contrary that the brightest cluster galaxy (BCG) is offset from the velocity center. To investigate the dynamical state of A2537 we obtain the redshift information of cluster galaxy candidates using Hectospec mounted on the MMT 6.5 m and compile those in the literature. The velocity distribution of member galaxies appears bimodal, with the main peak including the BCG and a secondary peak at velocity difference ~2000 km s-1. Based on the three-dimensional analysis and statistical tests we conclude that A2537 has at least two substructures and is not fully relaxed from a merger near the line-of-sight. We discuss more about the dynamical state of A2537 based on the color-magnitude diagram and X-ray scaling relation.