We spectroscopically survey the galaxy cluster XMM-LSS J02182-05102 ( hereafter IRC 0218 ) using LRIS ( optical ) and MOSFIRE ( near-infrared ) on Keck I as part of the ZFIRE survey .
IRC 0218 has a narrow redshift range of 1.612 < z _ { spec } < 1.635 defined by 33 members of which 20 are at R _ { proj } < 1 Mpc .
The cluster redshift and velocity dispersion are z _ { cl } = 1.6233 \pm 0.0003 and \sigma _ { cl } = 254 \pm 50 km s ^ { -1 } .
We reach NIR line sensitivities of \sim 0.3 \times 10 ^ { -17 } erg s ^ { -1 } cm ^ { -2 } that , combined with multi-wavelength photometry , provide extinction-corrected H \alpha star formation rates ( SFR ) , gas phase metallicities from [ N ii ] /H \alpha , and stellar masses .
We measure an integrated H \alpha SFR of \sim 325 { M } _ { \odot } yr ^ { -1 } ( 26 members ; R _ { proj } < 2 Mpc ) and show that the elevated star formation in the cluster core ( R _ { proj } < 0.25 Mpc ) is driven by the concentration of star-forming members , but the average SFR per H \alpha -detected galaxy is half that of members at R _ { proj } \sim 1 Mpc .
However , we do not detect any environmental imprint when comparing attenuation and gas phase metallicities : the cluster galaxies show similar trends with { M } _ { \star } as to the field , e.g .
more massive galaxies have larger stellar attenuation .
IRC 0218 ’ s gas phase metallicity- { M } _ { \star } relation ( MZR ) is offset to lower metallicities relative to z \sim 0 and has a slope of 0.13 \pm 0.10 .
Comparing the MZR in IRC 0218 to the COSMOS cluster at z = 2.1 shows no evolution ( \Delta t \sim 1 Gyr ) : the MZR for both galaxy clusters are remarkably consistent with each other and virtually identical to several field surveys at z \sim 2 .