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  • ZFIRE: Galaxy Cluster Kinematics, H alpha Star Formation Rates, and Gas Phase Metallicities of XMM-LSS J02182-05102 at zcl = 1.6232

ZFIRE: Galaxy Cluster Kinematics, H alpha Star Formation Rates, and Gas Phase Metallicities of XMM-LSS J02182-05102 at zcl = 1.6232


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 < zspec < 1.635 defined by 33 members of which 20 are at Rproj < 1 Mpc. The cluster redshift and velocity dispersion are zcl = 1.6233+/- 0.0003 and σcl = 254+/- 50 km s-1. We reach NIR line sensitivities of  ~0.3 × 10-17 erg s-1 cm-2 that, combined with multi-wavelength photometry, provide extinction-corrected Hα star formation rates (SFR), gas phase metallicities from [N ii]/Hα, and stellar masses. We measure an integrated Hα SFR of  ~325 Myr-1 (26 members; Rproj < 2 Mpc) and show that the elevated star formation in the cluster core (Rproj < 0.25 Mpc) is driven by the concentration of star-forming members, but the average SFR per Hα-detected galaxy is half that of members at Rproj ~ 1 Mpc. However, we do not detect any environmental imprint when comparing attenuation and gas phase metallicities: the cluster galaxies show similar trends with Mstar as to the field, e.g., more massive galaxies have larger stellar attenuation. IRC 0218’s gas phase metallicity-Mstar relation (MZR) is offset to lower metallicities relative to z ~ 0 and has a slope of 0.13 ± 0.10. Comparing the MZR in IRC 0218 to the COSMOS cluster at z = 2.1 shows no evolution (Δt ~ 1 Gyr): the MZR for both galaxy clusters are remarkably consistent with each other and virtually identical to several field surveys at z ~ 2

Astrophysical Journal, 811, 28, 2015

Kim-Vy H. Tran, Themiya Nanayakkara, Tiantian Yuan, Glenn G. Kacprzak, Karl Glazebrook, Lisa J. Kewley, Ivelina Momcheva, Casey J. Papovich, Ryan Quadri, Greg Rudnick*, Amélie Saintonge, Lee R. Spitler, Caroline Straatman, and Adam Tomczak *KU Author

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