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

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^{+0.25}{-0.22}\times 10^{15} \ h^{-1}{70}
$\text{M}${\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^{+0.15}{-0.13}\times 10^{14} \ h^{-1}{70}
$\text{M}${\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^{+0.22}{-0.20}\times 10^{14} \ h^{-1}{70} \ $\text{M}${\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^{+0.24}{-0.22}\times 10^{14} \ h^{-1}{70}
$\text{M}$_{\odot}$, is northwest of the X-ray peak and beyond the NW radio relic.