The MOSDEF survey: direct-method metallicities and ISM conditions at z ∼ 1.5–3.5
| Autor: | Irene Shivaei, Naveen A. Reddy, Bahram Mobasher, Mariska Kriek, Sedona H. Price, Gene C. K. Leung, Ryan L. Sanders, William R. Freeman, Tom Zick, Francesca M. Fornasini, Guillermo Barro, Brian Siana, Tara Fetherolf, Mojegan Azadi, Alison L. Coil, Laura de Groot, Alice E. Shapley |
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| Rok vydání: | 2019 |
| Předmět: |
Physics
010308 nuclear & particles physics Metallicity FOS: Physical sciences Binary number Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Photoionization Astrophysics Astrophysics - Astrophysics of Galaxies 01 natural sciences Galaxy Redshift Stars Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Ionization 0103 physical sciences Astrophysics::Earth and Planetary Astrophysics 010303 astronomy & astrophysics Reionization Astrophysics::Galaxy Astrophysics |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 491:1427-1455 |
| ISSN: | 1365-2966 0035-8711 |
| Popis: | We present detections of [OIII]$��$4363 and direct-method metallicities for star-forming galaxies at $z=1.7-3.6$. We combine new measurements from the MOSFIRE Deep Evolution Field (MOSDEF) survey with literature sources to construct a sample of 18 galaxies with direct-method metallicities at $z>1$, spanning $7.51$ sample on average. We construct the first mass-metallicity relation at $z>1$ based purely on direct-method O/H, finding a slope that is consistent with strong-line results. Direct-method O/H evolves by $\lesssim0.1$ dex at fixed M$_*$ and SFR from $z\sim0-2.2$. We employ photoionization models to constrain the ionization parameter and ionizing spectrum in the high-redshift sample. Stellar models with super-solar O/Fe and binary evolution of massive stars are required to reproduce the observed strong-line ratios. We find that the $z>1$ sample falls on the $z\sim0$ relation between ionization parameter and O/H, suggesting no evolution of this relation from $z\sim0$ to $z\sim2$. These results suggest that the offset of the strong-line ratios of this sample from local excitation sequences is driven primarily by a harder ionizing spectrum at fixed nebular metallicity compared to what is typical at $z\sim0$, naturally explained by super-solar O/Fe at high redshift caused by rapid formation timescales. Given the extreme nature of our $z>1$ sample, the implications for representative $z\sim2$ galaxy samples at $\sim10^{10}$ M$_{\odot}$ are unclear, but similarities to $z>6$ galaxies suggest that these conclusions can be extended to galaxies in the epoch of reionization. 27 pages + 4 page appendix, 18 figures, accepted for publication in MNRAS |
| Databáze: | OpenAIRE |
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