Optical identifications of high-redshift galaxy clusters from Planck Sunyaev-Zeldovich survey

TL;DR

This paper reports optical identifications and spectroscopic redshifts for high-redshift galaxy clusters from the Planck SZ survey, including discovery of gravitational lensing features and doubling known high-z clusters.

Contribution

It provides new optical and spectroscopic data for high-redshift clusters from the Planck SZ catalog, including redshift measurements and lensing observations.

Findings

Spectroscopic redshifts obtained for seven clusters.

Discovery of gravitational lensing features at z=4.262.

Number of known high-redshift clusters roughly doubled.

Abstract

We present the results of optical identifications and spectroscopic redshifts measurements for galaxy clusters from 2-nd Planck catalogue of Sunyaev-Zeldovich sources (PSZ2), located at high redshifts, $z\approx0.7-0.9$. We used the data of optical observations obtained with Russian-Turkish 1.5-m telescope (RTT150), Sayan observatory 1.6-m telescope, Calar Alto 3.5-m telescope and 6-m SAO RAS telescope (Bolshoi Teleskop Alt-azimutalnyi, BTA). Spectroscopic redshift measurements were obtained for seven galaxy clusters, including one cluster, PSZ2 G126.57+51.61, from the cosmological sample of PSZ2 catalogue. In central regions of two clusters, PSZ2 G069.39+68.05 and PSZ2 G087.39-34.58, the strong gravitationally lensed background galaxies are found, one of them at redshift $z=4.262$. The data presented below roughly double the number of known galaxy clusters in the second Planck catalogue of Sunyaev-Zeldovich sources at high redshifts, $z\approx0.8$.