Galaxy Clusters at z ≥ 1: Gas Constraints from the Sunyaev–Zel'dovich Array

Abstract

We present gas constraints from Sunyaev-Zel'dovich (SZ) effect measurements in a sample of 11 X-ray and infrared (IR) selected galaxy clusters at z ≥ 1, using data from the Sunyaev-Zel'dovich Array (SZA). The cylindrically integrated Compton-y parameter, Y, is calculated by fitting the data to a two-parameter gas pressure profile. Where possible, we also determine the temperature of the hot intracluster plasma from Chandra and XMM-Newton data and constrain the gas mass within the same aperture (r_(2500)) as Y. The SZ effect is detected in the clusters for which the X-ray data indicate gas masses above ~10^(13) M _⊙, including XMMU J2235 – 2557 at redshift z = 1.39, which to date is one of the most distant clusters detected using the SZ effect. None of the IR-selected targets are detected by the SZA measurements, indicating low gas masses for these objects. For these and the four other undetected clusters, we quote upper limits on Y and M_(gas,SZ), with the latter derived from scaling relations calibrated with lower redshift clusters. We compare the constraints on Y and X-ray-derived gas mass M_(gas,X-ray) to self-similar scaling relations between these observables determined from observations of lower redshift clusters, finding consistency given the measurement error.

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