The investigation of merging galaxy clusters that exhibit radio relics is strengthening our understanding of the formation and evolution of galaxy clusters, the nature of dark matter, the intracluster medium, and astrophysical particle acceleration. Each merging cluster provides only a single view of the cluster formation process, and the variety of merging clusters is vast. Clusters hosting double radio relics are rare and extremely important because they allow tight constraints on the merger scenario. We present a weak-lensing and X-ray analysis of MACS J1752.0+4440 (z = 0.365) and ZWCL 1856.8+6616 (z = 0.304), two double radio relic clusters. Our weak-lensing mass estimates show that each cluster is a major merger with approximately 1:1 mass ratio. The total mass of MACS J1752.0+4440 (ZWCL 1856.8+6616) is M200 = 14.7-+3.33.8 ´ 1014 Me (M200 = 2.4-+0.70.9 ´ 1014 Me). We find that these two clusters have comparable features in their weak-lensing and gas distributions, even though the systems have vastly different total masses. From the likeness of the X-ray morphologies and the remarkable symmetry of the radio relics, we propose that both systems underwent nearly head-on collisions. However, revelations from the hot-gas features and our multiwavelength data analysis suggest that ZWCL 1856.8+6618 is likely at a later merger phase than MACS J1752.0+4440. We postulate that the SW radio relic in MACS J1752.0 +4440 is a result of particle reacceleration.
Bibliographical noteFunding Information:
This work is based on observations made with the NASA/ ESA Hubble Space Telescope and operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-2655. M.J.J. acknowledges support from the National Research Foundation of Korea under program nos. 2017R1A2B2004644 and 2017R1A4A1015178. Part of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
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All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science