CARMA observations of massive Planck-discovered cluster candidates at z>0.5 associated with WISE overdensities: strategy, observations and validation

TL;DR

This study uses CARMA-8 31-GHz observations to confirm and analyze 19 Planck cluster candidates with WISE overdensities, detecting SZ signals in 9 cases and assessing their redshifts and environments.

Contribution

It provides the first high-resolution SZ observations of Planck-WISE selected cluster candidates, validating their nature and exploring their redshift distribution.

Findings

SZ detection in 9 out of 19 candidates

Most clusters likely at 0.3<z<0.7

One cluster matches known Abell 586

Abstract

We present 1-2 arcmin spatial resolution CARMA-8 31-GHz observations towards 19 unconfirmed Planck cluster candidates, selected to have significant galaxy overdensities from the WISE early data release and thought to be at z>1 from the WISE colors of the putative brightest cluster galaxy (BCG). We find a Sunyaev-Zeldovich (SZ) detection in the CARMA-8 data towards 9 candidate clusters, where one detection is considered tentative. For each cluster candidate we present CARMA-8 maps, a study of their radio-source environment and we assess the reliability of the SZ detection. The CARMA SZ detections appear to be SZ-bright, with the mean, primary-beam-corrected peak flux density of the decrement being -2.9mJy/beam with a standard deviation of 0.8, and are typically offset from the Planck position by approximately 80 arcsec. Using archival imaging data in the vicinity of the CARMA SZ centroids, we present evidence that one cluster matches Abell 586-a known z~0.2 cluster; four candidate clusters are likely to have 0.3<z<0.7; and, for the remaining 4, the redshift information is inconclusive. We also argue that the sensitivity limits resulting from the cross-correlation between Planck and WISE makes it challenging to use our selection criterion to identify clusters at z > 1.