The Massive and Distant Clusters of WISE Survey: MOO J1142+1527, a 1015 M⊙ Galaxy Cluster at z = 1.19

We present confirmation of the cluster MOO J1142+1527, a massive galaxy cluster discovered as part of the Massive and Distant Clusters of WISE Survey. The cluster is confirmed to lie at z = 1.19, and using the Combined Array for Research in Millimeter-wave Astronomy we robustly detect the Sunyaev-Zel’dovich (SZ) decrement at 13.2σ. The SZ data imply a mass of M_200m = (1.1 ± 0.2) × 10¹⁵M_⊙, making MOO J1142+1527 the most massive galaxy cluster known at z > 1.15 and the second most massive cluster known at z > 1. For a standard ΛCDM cosmology it is further expected to be one of the ∼5 most massive clusters expected to exist at z ≥ 1.19 over the entire sky. Our ongoing Spitzer program targeting ∼1750 additional candidate clusters will identify comparably rich galaxy clusters over the full extragalactic sky.