Substructures within Substructures in the Complex Postmerging System A514 Unveiled by High-resolution Magellan/Megacam Weak Lensing

Abstract

Abell 514 (A514) at z = 0.071 is an intriguing merging system exhibiting highly elongated (∼1 Mpc) X-ray features and three large-scale (300 ∼ 500 kpc) bent radio jets. To dissect this system with its multiwavelength data, it is critical to robustly identify and quantify its dark matter substructures. We present a weak-lensing analysis of A514 using deep Magellan/Megacam observations. Combining two optical band filter imaging data obtained under optimal seeing (∼0.″6) and leveraging the proximity of A514, we achieve a high source density of $\sim 46\,{{\rm{arcmin}}}^{-2}$ or ∼6940 Mpc ^−2 , which enables high-resolution mass reconstruction. We unveil the complex dark matter substructures of A514, which are characterized by the NW and SE subclusters separated by ∼0.7 Mpc, each exhibiting a bimodal mass distribution. The total mass of the NW subcluster is estimated to be ${M}_{200c}^{\mathrm{NW}}={1.08}_{-0.22}^{+0.25}\times {10}^{14}{M}_{\odot }$ and is further resolved into the eastern ( ${M}_{200c}^{{\mathrm{NW}}_{{\rm{E}}}}={2.6}_{-1.1}^{+1.4}\times {10}^{13}{M}_{\odot })$ and western ( ${M}_{200c}^{{\mathrm{NW}}_{{\rm{W}}}}={7.1}_{-2.0}^{+2.3}\times {10}^{13}{M}_{\odot }$ ) components. The mass of the SE subcluster is ${M}_{200c}^{\mathrm{SE}}={1.55}_{-0.26}^{+0.28}\times {10}^{14}{M}_{\odot }$ , which is also further resolved into the northern ( ${M}_{200c}^{{\mathrm{SE}}_{{\rm{N}}}}={2.9}_{-1.3}^{+1.8}\times {10}^{13}{M}_{\odot }$ ) and southern ( ${M}_{200c}^{{\mathrm{SE}}_{{\rm{S}}}}={8.5}_{-2.6}^{+3.1}\times {10}^{13}{M}_{\odot }$ ) components. These four substructures coincide with the A514 brightest galaxies and are detected with significances ranging from 3.3 σ to 4.7 σ . Comparison of the dark matter substructures with the X-ray distribution suggests that A514 might have experienced an off-axis collision, and the NW and SE subclusters are currently near their apocenters.

Keywords

• Abell clusters
• Weak gravitational lensing
• Galaxy clusters
• Dark matter