Abstract
We present a detailed analysis of 317 2.0 ≤ z ≤ 2.7 star-forming galaxies from the Keck Baryonic Structure Survey. Using complementary spectroscopic observations with Keck/LRIS and Keck/MOSFIRE, as well as spectral energy distribution (SED) fits to broadband photometry, we examine the joint rest-UV and rest-optical properties of the same galaxies, including stellar and nebular dust attenuation, metallicity, and star formation rate (SFR). The inferred parameters of the stellar population (reddening, age, SFR, and stellar mass) are strongly dependent on the details of the assumed stellar population model and the shape of the attenuation curve. Nebular reddening is generally larger than continuum reddening, but with large scatter. Compared to local galaxies, high-redshift galaxies have lower gas-phase metallicities (and/or higher nebular excitation) at fixed nebular reddening, and higher nebular reddening at fixed stellar mass, consistent with gas fractions that increase with redshift. We find that continuum reddening is correlated with 12 + log(O/H) O3N2 at 3.0σ significance, whereas nebular reddening is correlated with only 1.1σ significance. This may reflect the dependence of both continuum reddening and O3N2 on the shape of the ionizing radiation field produced by the massive stars. Finally, we show that Hα-based and SED-based estimates of SFR exhibit significant scatter relative to one another, and on average agree only for particular combinations of spectral synthesis models and attenuation curves. We find that the SMC extinction curve predicts consistent SFRs if we assume the subsolar (0.14 Z o ) binary star models that are favored for high-redshift galaxies.
| Original language | English (US) |
|---|---|
| Article number | 128 |
| Journal | Astrophysical Journal |
| Volume | 871 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 20 2019 |
Funding
The authors thank Max Pettini and the anonymous referee for helpful comments. This work has been supported in part by the NSF through grants AST-0908805 and AST-1313472 (CCS, RLT, ALS), by the JPL President-Director Fund (CCS, RLT), by the Professor Wallace L. W. Sargent Graduate Fellowship (RLT) and the Troesh Family Distinguished Scholars Fund (also RLT), and by an Alfred P. Sloan Research Fellowship (NAR). 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.
Keywords
- HII regions
- ISM: Abundances
- dust, extinction
- galaxies: Evolution
- galaxies: High-redshift
- galaxies: Star formation
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science