MC${}^2$: Subaru and Hubble Space Telescope Weak-Lensing Analysis of the Double Radio Relic Galaxy Cluster PLCK G287.0+32.9

Abstract

The second most significant detection of the Planck Sunyaev Zel'dovich survey, PLCK~G287.0+32.9 ($z=0.385$) boasts two similarly bright radio relics and a radio halo. One radio relic is located $\sim 400$ kpc northwest of the X-ray peak and the other $\sim 2.8$ Mpc to the southeast. This large difference suggests that a complex merging scenario is required. A key missing puzzle for the merging scenario reconstruction is the underlying dark matter distribution in high resolution. We present a joint Subaru Telescope and {\it Hubble Space Telescope} weak-lensing analysis of the cluster. Our analysis shows that the mass distribution features four significant substructures. Of the substructures, a primary cluster of mass $M_{200\text{c}}=1.59_{-0.22}^{+0.25}\times 10^{15}{h}_{70}^{-1}{\text{M}}_{\odot }$ dominates the weak-lensing signal. This cluster is likely to be undergoing a merger with one (or more) subcluster whose mass is approximately a factor of 10 lower. One candidate is the subcluster of mass $M_{200\text{c}}=1.16_{-0.13}^{+0.15}\times 10^{14}{h}_{70}^{-1}{\text{M}}_{\odot }$ located $\sim 400$ kpc to the southeast. The location of this subcluster suggests that its interaction with the primary cluster could be the source of the NW radio relic. Another subcluster is detected $\sim 2$ Mpc to the SE of the X-ray peak with mass $M_{200\text{c}}=1.68_{-0.20}^{+0.22}\times 10^{14}{h}_{70}^{-1}{\text{M}}_{\odot }$. This SE subcluster is in the vicinity of the SE radio relic and may have created the SE radio relic during a past merger with the primary cluster. The fourth subcluster, $M_{200\text{c}}=1.87_{-0.22}^{+0.24}\times 10^{14}{h}_{70}^{-1}{\text{M}}_{\odot }$, is northwest of the X-ray peak and beyond the NW radio relic.

19 pages, 14 figures; Accepted to ApJ