Spectroscopic confirmation and velocity dispersions for twenty Planck galaxy clusters at 0.16<z<0.78

TL;DR

This paper reports spectroscopic redshifts and velocity dispersions for twenty galaxy clusters detected by Planck via the Sunyaev-Zel'dovich effect, including the confirmation of one of the most distant clusters to date, aiding in mass bias analysis.

Contribution

First spectroscopic follow-up for twenty Planck SZ clusters, including seven new redshifts and the confirmation of a distant cluster at z=0.782, expanding the dataset for cluster mass studies.

Findings

Seven new cluster redshifts measured.

Confirmed a distant cluster at z=0.782.

Velocity dispersions used to analyze mass bias.

Abstract

We present Gemini and Keck spectroscopic redshifts and velocity dispersions for twenty clusters detected via the Sunyaev-Zel'dovich (SZ) effect by the Planck space mission, with estimated masses in the range $2.3 \times 10^{14} M_{\odot} < M < 9.4 \times 10^{14} M_{\odot}$. Cluster members were selected for spectroscopic follow-up with Palomar, Gemini and Keck optical and (in some cases) infrared imaging. Seven cluster redshifts were measured for the first time with this observing campaign, including one of the most distant Planck clusters confirmed to date, at $z=0.782\pm0.010$, PSZ2 G085.95+25.23. The spectroscopic redshift catalogs of members of each confirmed cluster are included as on-line tables. We show the galaxy redshift distributions and measure the cluster velocity dispersions. The cluster velocity dispersions obtained in this paper were used in a companion paper to measure the Planck mass bias and to constrain the cluster velocity bias.