%0 Generic %1 strom2017measuring %A Strom, Allison L. %A Steidel, Charles C. %A Rudie, Gwen C. %A Trainor, Ryan F. %A Pettini, Max %D 2017 %K ISM galaxies high redshift %T Measuring the Physical Conditions in High-Redshift Star-Forming Galaxies: Insights from KBSS-MOSFIRE %U http://arxiv.org/abs/1711.08820 %X We use photoionization models designed to reconcile the joint rest-UV-optical spectra of high-z star-forming galaxies to self-consistently infer the gas chemistry and nebular ionization and excitation conditions for ~160 galaxies from the Keck Baryonic Structure Survey (KBSS), using only observations of their rest-optical nebular spectra. We find that the majority of z~2-3 KBSS galaxies are moderately O-rich, with an interquartile range in 12+log(O/H)=8.29-8.55, and have significantly sub-solar Fe enrichment, with an interquartile range of Fe/H=-0.82,-0.54, contributing additional evidence in favor of super-solar O/Fe in high-z galaxies. Ionization parameter and N/O, as determined through comparisons with the photoionization models, are strongly correlated with common strong-line indices (such as O32 and N2O2), whereas diagnostics commonly used for measuring gas-phase O/H (such as N2 and O3N2) are relatively insensitive to the overall amount of oxygen present in the gas. We provide a new calibration using R23 to measure O/H in typical high-z galaxies, although it is most useful for relatively O-rich galaxies; combining O32 and R23 does not yield a more effective calibration. Finally, we consider implications for the intrinsic correlations between physical conditions across the galaxy sample and find that N/O varies with O/H in high-z galaxies in a manner almost identical to local extragalactic HII regions. In contrast, we do not find a strong anti-correlation between ionization parameter and metallicity (O/H or Fe/H) in high-z galaxies, which is one of the principal bases for using strong-line ratios to infer oxygen abundance.

@misc{strom2017measuring, abstract = {We use photoionization models designed to reconcile the joint rest-UV-optical spectra of high-z star-forming galaxies to self-consistently infer the gas chemistry and nebular ionization and excitation conditions for ~160 galaxies from the Keck Baryonic Structure Survey (KBSS), using only observations of their rest-optical nebular spectra. We find that the majority of z~2-3 KBSS galaxies are moderately O-rich, with an interquartile range in 12+log(O/H)=8.29-8.55, and have significantly sub-solar Fe enrichment, with an interquartile range of [Fe/H]=[-0.82,-0.54], contributing additional evidence in favor of super-solar O/Fe in high-z galaxies. Ionization parameter and N/O, as determined through comparisons with the photoionization models, are strongly correlated with common strong-line indices (such as O32 and N2O2), whereas diagnostics commonly used for measuring gas-phase O/H (such as N2 and O3N2) are relatively insensitive to the overall amount of oxygen present in the gas. We provide a new calibration using R23 to measure O/H in typical high-z galaxies, although it is most useful for relatively O-rich galaxies; combining O32 and R23 does not yield a more effective calibration. Finally, we consider implications for the intrinsic correlations between physical conditions across the galaxy sample and find that N/O varies with O/H in high-z galaxies in a manner almost identical to local extragalactic HII regions. In contrast, we do not find a strong anti-correlation between ionization parameter and metallicity (O/H or Fe/H) in high-z galaxies, which is one of the principal bases for using strong-line ratios to infer oxygen abundance.}, added-at = {2017-11-27T10:21:35.000+0100}, author = {Strom, Allison L. and Steidel, Charles C. and Rudie, Gwen C. and Trainor, Ryan F. and Pettini, Max}, biburl = {https://www.bibsonomy.org/bibtex/2a85e88e1a89841a29e0f4826ee3762f3/miki}, description = {[1711.08820] Measuring the Physical Conditions in High-Redshift Star-Forming Galaxies: Insights from KBSS-MOSFIRE}, interhash = {277a950cb4f5c622b87e8d6f646b5102}, intrahash = {a85e88e1a89841a29e0f4826ee3762f3}, keywords = {ISM galaxies high redshift}, note = {cite arxiv:1711.08820Comment: 24 pages, 20 figures. Submitted to the Astrophysical Journal}, timestamp = {2017-11-27T10:21:35.000+0100}, title = {Measuring the Physical Conditions in High-Redshift Star-Forming Galaxies: Insights from KBSS-MOSFIRE}, url = {http://arxiv.org/abs/1711.08820}, year = 2017 }