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

Mohamed H. Abdullah; Omnia I. Adly; Gillian Wilson; Magdy Y. Amin; A. Ahmed

Paper

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 (R200), velocity dispersion (sigma200), and virial mass (M200) using the virial mass estimator. We identified ten VIPERS clusters spanning a mass range of 0.59 x 10^14 <= M200/(h^-1 Msun) <= 4.32 x 10^14 and velocity dispersions of 360 <= sigma200 <= 900 km s^-1. We cross-matched the VIPERS clusters with published catalogs and found at least one matching system for each cluster, offering external validation for our detections. We investigated the velocity dispersion-mass relation for these systems and obtained log(sigma200) = (2.73 +/- 0.06) + (0.36 +/- 0.18) log(M200), with an intrinsic scatter of sigma_int = 0.04 +/- 0.07. The derived relation is consistent with theoretical predictions from N-body and hydrodynamical simulations, confirming the reliability of the FoG-GalWeight methodology and the robustness of the virial mass estimator. Our findings demonstrate that the velocity dispersion can serve as a reliable and direct proxy for cluster mass, even at high redshift, without requiring additional dynamical mass modeling.