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arXiv · 1606.04107

The MOSDEF Survey: Detection of [OIII]$\lambda$4363 and the direct-method oxygen abundance of a star-forming galaxy at z=3.08

Ryan L. Sanders·Alice E. Shapley·Mariska Kriek·Naveen A. Reddy·William R. Freeman·Alison L. Coil·Brian Siana·Bahram Mobasher·Irene Shivaei·Sedona H. Price·Laura de Groot
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Abstract

We present measurements of the electron-temperature based oxygen abundance for a highly star-forming galaxy at z=3.08, COSMOS-1908. This is the highest redshift at which [OIII]$\lambda$4363 has been detected, and the first time that this line has been measured at z>2. We estimate an oxygen abundance of 12+log(O/H)$=8.00^{+0.13}_{-0.14}$. This galaxy is a low-mass ($10^{9.3}$ M$_{\odot}$), highly star-forming ($\sim50$ M$_{\odot}$ yr$^{-1}$) system that hosts a young stellar population ($\sim160$ Myr). We investigate the physical conditions of the ionized gas in COSMOS-1908 and find that this galaxy has a high ionization parameter, little nebular reddening ($E(B-V)_{\rm gas}<0.14$), and a high electron density ($n_e\sim500$ cm$^{-3}$). We compare the ratios of strong oxygen, neon, and hydrogen lines to the direct-method oxygen abundance for COSMOS-1908 and additional star-forming galaxies at z=0-1.8 with [OIII]$\lambda$4363 measurements, and show that galaxies at z$\sim$1-3 follow the same strong-line correlations as galaxies in the local universe. This agreement suggests that the relationship between ionization parameter and O/H is similar for z$\sim$0 and high-redshift galaxies. These results imply that metallicity calibrations based on lines of oxygen, neon, and hydrogen do not strongly evolve with redshift and can reliably estimate abundances out to z$\sim$3, paving the way for robust measurements of the evolution of the mass-metallicity relation to high redshift.

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Ryan L. Sanders, Alice E. Shapley, Mariska Kriek, Naveen A. Reddy, William R. Freeman, Alison L. Coil, Brian Siana, Bahram Mobasher, Irene Shivaei, Sedona H. Price, Laura de Groot. 2016-06-13. The MOSDEF Survey: Detection of [OIII]$\lambda$4363 and the direct-method oxygen abundance of a star-forming galaxy at z=3.08. https://doi.org/10.3847/2041-8205/825/2/l23

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