IDCS J1426+3508: Discovery of a Massive, IR-Selected Galaxy Cluster at z = 1.75

TL;DR

This paper reports the discovery and confirmation of a very massive galaxy cluster at redshift 1.75, identified through infrared selection and supported by multi-wavelength observations including X-ray data.

Contribution

It presents the first spectroscopic confirmation of a massive galaxy cluster at z=1.75 with detailed X-ray measurements, demonstrating the effectiveness of IR selection for high-redshift cluster detection.

Findings

Cluster confirmed at z=1.75 with spectroscopic data.

X-ray luminosity indicates a mass of approximately 5.6 x 10^{14} solar masses.

Cluster is exceptionally massive for its redshift.

Abstract

We report the discovery of an IR-selected massive galaxy cluster in the IRAC Distant Cluster Survey (IDCS). We present new data from the Hubble Space Telescope and the W. M. Keck Observatory that spectroscopically confirm IDCS J1426+3508 at z=1.75. Moreover, the cluster is detected in archival Chandra data as an extended X-ray source, comprising 54 counts after the removal of point sources. We calculate an X-ray luminosity of L{0.5-2 keV} = (5.5 +/- 1.2) X 1e44 ergs/s within r = 60 arcsec (~1 Mpc diameter), which implies M_{200,L_x} = (5.6 +/- 1.6) X 1e14 Msun. IDCS J1426+3508 appears to be an exceptionally massive cluster for its redshift.