Probing Saraswati's heart: evaluating the dynamical state of the massive galaxy cluster A2631 through a comprehensive weak-lensing and dynamical analysis

TL;DR

This study assesses the dynamical state of galaxy cluster Abell 2631 using combined weak-lensing and dynamical analyses, resolving previous mass measurement tensions and suggesting a late-stage merging scenario.

Contribution

It presents a comprehensive weak-lensing analysis combining shear and magnification data, and reconciles mass estimates with galaxy dynamics and X-ray observations.

Findings

Weak-lensing mass: $8.7_{-2.9}^{+2.5} imes 10^{14}$ M$_\odot$

Dynamical mass: $12.2\pm3.0 imes 10^{14}$ M$_\odot$

Cluster observed at a late merging stage

Abstract

In this work, we investigate the dynamical state of the galaxy cluster Abell 2631, a massive structure located at the core of the Saraswati supercluster. To do this, we first solve a tension found in the literature regarding the weak-lensing mass determination of the cluster. We do this through a comprehensive weak-lensing analysis, exploring the power of the combination of shear and magnification data sets. We find $M_{200}^{\rm wl} = 8.7_{-2.9}^{+2.5} \times 10^{14}$ M$_\odot$. We also determined the mass based on the dynamics of spectroscopic members, corresponding to $M_{200}^{\rm dy} = 12.2\pm3.0 \times 10^{14}$ M$_\odot$, consistent within a 68 per cent CL with the weak-lensing estimate. The scenarios provided by the mass distribution and dynamics of galaxies are reconciled with those provided by X-ray observations in a scenario where A2631 is observed at a late stage of merging.