A Caltech Library Service

Measuring the Physical Conditions in High-redshift Star-forming Galaxies: Insights from KBSS-MOSFIRE

Strom, Allison L. and Steidel, Charles C. and Rudie, Gwen C. and Trainor, Ryan F. and Pettini, Max (2018) Measuring the Physical Conditions in High-redshift Star-forming Galaxies: Insights from KBSS-MOSFIRE. Astrophysical Journal, 868 (2). Art. No. 117. ISSN 1538-4357. doi:10.3847/1538-4357/aae1a5.

[img] PDF - Published Version
See Usage Policy.

[img] PDF - Accepted Version
See Usage Policy.


Use this Persistent URL to link to this item:


We use photoionization models that are 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 ~150 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) = 8.29–8.56, and have significantly sub-solar Fe enrichment, with an interquartile range of [Fe/H] = [−0.79, −0.53], which contributes additional evidence in favor of super-solar O/Fe in high-z galaxies. The model-inferred ionization parameters and N/O are strongly correlated with common strong-line indices (such as O32 and N2O2), with the latter exhibiting similar behavior to local extragalactic H ii regions. In contrast, diagnostics commonly used for measuring gas-phase O/H (such as N2 and O3N2) show relatively large scatter with the overall amount of oxygen present in the gas and behave differently than observed at z ~ 0. We provide a new calibration for 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 the 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 that is almost identical to local H ii regions. However, 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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Strom, Allison L.0000-0001-6369-1636
Steidel, Charles C.0000-0002-4834-7260
Rudie, Gwen C.0000-0002-8459-5413
Trainor, Ryan F.0000-0002-6967-7322
Pettini, Max0000-0002-5139-4359
Additional Information:© 2018. The American Astronomical Society. Received 2017 November 20; revised 2018 September 3; accepted 2018 September 12; published 2018 November 29. The data presented in this paper were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. This work has been supported in part by a US National Science Foundation (NSF) Graduate Research Fellowship (A.L.S.), by the NSF through grants AST-0908805 and AST-1313472 (C.C.S. and A.L.S.). Finally, the authors wish to recognize and acknowledge the significant cultural role and reverence that the summit of Maunakea has within the indigenous Hawaiian community. We are privileged to have the opportunity to conduct observations from this mountain.
Group:Astronomy Department
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Subject Keywords:cosmology: observations; galaxies: evolution; galaxies: ISM; galaxies: high-redshift; H ii regions; ISM: abundances
Issue or Number:2
Record Number:CaltechAUTHORS:20181129-110052473
Persistent URL:
Official Citation:Allison L. Strom et al 2018 ApJ 868 117
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91329
Deposited By: George Porter
Deposited On:29 Nov 2018 19:15
Last Modified:16 Nov 2021 03:40

Repository Staff Only: item control page