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arXiv · 1306.6334

The Mass-Metallicity Relation Of A Z~2 Protocluster With MOSFIRE

Kristin R. Kulas·Ian S. McLean·Alice E. Shapley·Charles C. Steidel·Nicholas P. Konidaris·Keith Matthews·Gregory N. Mace·Gwen C. Rudie·Ryan F. Trainor·Naveen A. Reddy
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Abstract

We present Keck/MOSFIRE observations of the role of environment in the formation of galaxies at z~2. Using K-band spectroscopy of H-alpha and [N II] emission lines, we have analyzed the metallicities of galaxies within and around a z=2.3 protocluster discovered in the HS1700+643 field. Our main sample consists of 23 protocluster and 20 field galaxies with estimates of stellar masses and gas-phase metallicities based on the N2 strong-line metallicity indicator. With these data we have examined the mass-metallicity relation (MZR) with respect to environment at z~2. We find that field galaxies follow the well-established trend between stellar mass and metallicity, such that more massive galaxies have larger metallicities. The protocluster galaxies, however, do not exhibit a dependence of metallicity on mass, with the low-mass protocluster galaxies showing an enhancement in metallicity compared to field galaxies spanning the same mass range. A comparison with galaxy formation models suggests that the mass-dependent environmental trend we observed can be qualitatively explained in the context of the recycling of "momentum-driven" galaxy wind material. Accordingly, winds are recycled on a shorter timescale in denser environments, leading to an enhancement in metallicity at fixed mass for all but the most massive galaxies. Future hydrodynamical simulations of z~2 overdensities matching the one in the HS1700 field will be crucial for understanding the origin of the observed environmental trend in detail.

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Kristin R. Kulas, Ian S. McLean, Alice E. Shapley, Charles C. Steidel, Nicholas P. Konidaris, Keith Matthews, Gregory N. Mace, Gwen C. Rudie, Ryan F. Trainor, Naveen A. Reddy. 2013-06-26. The Mass-Metallicity Relation Of A Z~2 Protocluster With MOSFIRE. https://doi.org/10.1088/0004-637x/774/2/130

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