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arXiv · 1904.12090

A spectroscopic study of a rich cluster at z=1.52 with Subaru $\&$ LBT: the environmental impacts on the mass-metallicity relation

Shigeru V. Namiki·Yusei Koyama·Masao Hayashi·Ken-ichi Tadaki·Nobunari Kashikawa·Masato Onodera·Rhythm Shimakawa·Tadayuki Kodama·Ichi Tanaka·N. M. Förster Schreiber·Jaron Kurk·R. Genzel
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Abstract

We present the results of our near-infrared (NIR) spectroscopic observations of a rich cluster candidate around a radio galaxy at $z=1.52$ (4C65.22) with Subaru/MOIRCS and LBT/LUCI. We observed 71 galaxies mostly on the star-forming main sequence selected by our previous broad-band (photo-$z$) and narrow-band H$\alpha$ imaging observation in this cluster environment. We successfully confirmed the redshifts of 39 galaxies, and conclude that this is a gravitationally bound, real cluster at $z=1.517$. Our spectroscopic data also suggest a hint of large-scale filaments or sheet-like three-dimensional structures crossing at the highest-density cluster core. By stacking the spectra to derive their average interstellar medium (ISM) gas-phase metallicity based on the [NII]/H$\alpha$ emission line flux ratio, we find that the mass-metallicity relation (MZR) in the 4C65.22 cluster environment is consistent with that of H$\alpha$-selected field galaxies at similar redshifts. Our results suggest that the environmental impacts on the MZR is small at high redshifts, but a larger sample of high-$z$ clusters and their member galaxies is still required to fully address the effect of environment as well as its cluster-cluster variation.

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Shigeru V. Namiki, Yusei Koyama, Masao Hayashi, Ken-ichi Tadaki, Nobunari Kashikawa, Masato Onodera, Rhythm Shimakawa, Tadayuki Kodama, Ichi Tanaka, N. M. Förster Schreiber, Jaron Kurk, R. Genzel. 2019-04-27. A spectroscopic study of a rich cluster at z=1.52 with Subaru $\&$ LBT: the environmental impacts on the mass-metallicity relation. https://doi.org/10.3847/1538-4357%2Fab1b6c

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