CARMA Follow-up of the Northern Unconfirmed Planck Galaxy Cluster Candidates

Abstract

We present the Combined Array for Research in Millimeter-wave Astronomy (CARMA) observations of the three northern unconfirmed galaxy clusters discovered by the Planck satellite. We confirm the existence of two massive clusters (PLCKESZ G115.71+17.52 and PLCKESZ G121.11+57.01) at high significance. For these clusters, we present refined centroid locations from the 31 GHz CARMA data, as well as mass estimates obtained from a joint analysis of CARMA and Planck data. We do not detect the third candidate, PLCKESZ G189.84-37.24, and place an upper limit on its mass of M ₅₀₀ < 3.2 × 10¹⁴ M _⊙ at 68% confidence. Considering our data and the characteristics of the Planck Early Sunyaev-Zel'dovich (ESZ) Catalog, we conclude that this object is likely to be a cold-core object in the plane of our Galaxy. As a result, we estimate the purity of the ESZ Catalog to be greater than 99.5%.