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 ∼ 46 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 200 c NW = 1.08 − 0.22 + 0.25 × 10 14 M ⊙ and is further resolved into the eastern ( M 200 c NW E = 2.6 − 1.1 + 1.4 × 10 13 M ⊙ ) and western ( M 200 c NW W = 7.1 − 2.0 + 2.3 × 10 13 M ⊙ ) components. The mass of the SE subcluster is M 200 c SE = 1.55 − 0.26 + 0.28 × 10 14 M ⊙ , which is also further resolved into the northern ( M 200 c SE N = 2.9 − 1.3 + 1.8 × 10 13 M ⊙ ) and southern ( M 200 c SE S = 8.5 − 2.6 + 3.1 × 10 13 M ⊙ ) components. These four substructures coincide with the A514 brightest galaxies and are detected with significances ranging from 3.3σ to 4.7σ. 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.