Galaxy Cluster Detection and Dynamical Analysis in the VIPERS High-redshift Spectroscopic Survey

Abstract We present a dynamical analysis of galaxy clusters identified in the VIPERS spectroscopic survey within the redshift range 0.5 ≤ z ≤ 1.2. Cluster candidates were first detected as overdense regions in redshift space through the Finger-of-God (FoG) effect, and cluster membership was assigned using the GalWeight technique within the FoG–GalWeight methodology developed by our team. For each cluster, we derived the virial radius ( R 200 ), velocity dispersion ( σ 200 ), and virial mass ( M 200 ) using the virial mass estimator. We identified 10 VIPERS clusters spanning a mass range of 0.59 × 10 14 ≤ M 200 /( h −1 M ⊙ ) ≤ 4.32 × 10 14 and velocity dispersions of 360 ≲ σ 200 ≲ 900 km s −1 . We constructed a stacked rest-frame color–magnitude diagram for the cluster members and found a clear red sequence, with red galaxies more centrally concentrated than blue galaxies. As a consistency check on the recovered dynamical properties, we examined the velocity dispersion–mass relation and obtained log σ 200 = ( 2.73 ± 0.06 ) + ( 0.36 ± 0.18 ) log M 200 , with an intrinsic scatter of σ int = 0.04 ± 0.07. The recovered dynamical properties are broadly consistent with expectations from N -body and hydrodynamical simulations. We also cross-matched the VIPERS clusters with published catalogs and found at least one previously reported cluster candidate associated with each system. Overall, our results show that the FoG–GalWeight methodology, combined with the virial mass estimator, can successfully identify and characterize galaxy clusters in high-redshift spectroscopic surveys.