Abstract
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$_\rm
proj<1$ Mpc. The cluster redshift and velocity dispersion are $z_\rm
cl=1.6233\pm0.0003$ and $\sigma_cl=254\pm50$ km s$^-1$. We reach NIR
line sensitivities of $\sim0.3\times10^-17$ erg s$^-1$ cm$^-2$ that,
combined with multi-wavelength photometry, provide extinction-corrected
H$\alpha$ star formation rates (SFR), gas phase metallicities from
NII/H$\alpha$, and stellar masses. We measure an integrated H$\alpha$ SFR of
$\sim325M_ødot$ 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$_proj\sim1$ 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 $z\sim0$ and has a slope of
$0.13\pm0.10$. Comparing the MZR in IRC 0218 to the COSMOS cluster at $z=2.1$
shows no evolution ($\Delta t\sim1$ Gyr): the MZR for both galaxy clusters are
remarkably consistent with each other and virtually identical to several field
surveys at $z\sim2$.
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