A Spitzer-Selected Galaxy Cluster at z=1.62

Understand

We report the discovery of a galaxy cluster at z=1.62 located in the Spitzer Wide-Area Infrared Extragalactic survey XMM-LSS field.

• This structure was selected solely as an overdensity of galaxies with red Spitzer/IRAC colors, satisfying [3.6]-[4.5] > -0.1 AB mag.
• Photometric redshifts derived from Subaru XMM Deep Survey (BViz-bands), UKIRT Infrared Deep Survey-Ultra-Deep Survey (UKIDSS-UDS, JK-bands), and from the Spitzer Public UDS survey (3.6-8.0 micron) show that this cluster corresponds to a surface density of galaxies at z ~ 1.6 that is more than 20 sigma above the mean at this redshift.
• We obtained optical spectroscopic observations of galaxies in the cluster region using IMACS on the Magellan telescope.