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STRONG NEBULAR LINE RATIOS IN THE SPECTRA of z ∼ 2-3 STAR FORMING GALAXIES: FIRST RESULTS FROM KBSS-MOSFIRE
We present initial results of a deep near-IR spectroscopic survey covering the 15 fields of the Keck Baryonic Structure Survey using the recently commissioned MOSFIRE spectrometer on the Keck 1 telescope. Using photoionization models, we argue that the offset of the z ~ 2.3 BPT locus relative to tha...
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Published in: | The Astrophysical journal 2014-11, Vol.795 (2), p.1-40 |
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Main Authors: | , , , , , , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | We present initial results of a deep near-IR spectroscopic survey covering the 15 fields of the Keck Baryonic Structure Survey using the recently commissioned MOSFIRE spectrometer on the Keck 1 telescope. Using photoionization models, we argue that the offset of the z ~ 2.3 BPT locus relative to that at z ~ 0 is caused by a combination of harder stellar ionizing radiation field, higher ionization parameter, and higher N/O at a given O/H compared to most local galaxies, and that the position of a galaxy along the z ~ 23 star-forming BPT locus is surprisingly insensitive to gas-phase oxygen abundance. We critically assess the applicability at high redshift of commonly used strong line indices for estimating gas-phase metallicity, and consider the implications of the small intrinsic scatter of the empirical relationship between excitation-sensitive line indices and M sub(*) (i.e., the "mass-metallicity" relation) at z [Asymptotically = to] 23. |
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ISSN: | 1538-4357 0004-637X 1538-4357 |
DOI: | 10.1088/0004-637X/795/2/165 |