The Detection of [O III]4363 and the Direct Measurement of the Oxygen Abundance in a Lensed, Dwarf Galaxy at z=2.59
Abstract
The stellar mass - gas-phase metallicity relation (MZR), critical to constraining models of star formation and feedback, has not been well-measured below a stellar mass of 109 solar masses at high redshift. This project will extend the MZR down to ~107 solar masses using strong-line calibrations and rest-optical spectra - obtained with the MOSFIRE spectrograph on Keck I - of >100 dwarf galaxies, lensed by 3 foreground clusters, at 1.5 < z < 3.7. We will compare our estimates in this lower-end mass range with predictions from analytical models and simulations to better understand the processes controlling star formation and feedback. We are also studying the accuracy of locally-calibrated, strong-line metallicity indicators at high redshift. Our sample contains a 107.8 solar mass, [O III]4363 source at z=2.59, with which we have calculated and compared a direct, Te-based metallicity estimate (12+log(O/H) = 7.98 +/- 0.20) with locally-calibrated strong-line estimates. We find that our direct metallicity estimate is consistent with local calibrations as well as with the positions of other low, intermediate, and high-redshift galaxies along these strong-line - direct metallicity relations. While the scatter is large in these relations, our findings support that these strong-line methods are accurate at high redshift. We also show that this galaxy lies roughly 1.5 sigma above a slight extrapolation of the low-mass end of the Fundamental Metallicity Relation (FMR), though it is likely consistent within this end's large scatter. Deeper exposures of our sample will lead to additional [O III]4363 detections or limits that will better constrain this low-mass end of the FMR and strong-line calibrations at high redshift.
- Publication:
-
American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019
- Bibcode:
- 2019AAS...23314519G