Recalibrating Strong-Line Metallicity Diagnostics: Chemical Abundances from Composite Galaxy Spectra

This talk was presented on 2019 April 13 at the 2018-19 NASA Arizona Space Grant Symposium. The event was located at the Doubletree by Hilton in Tempe, Arizona (USA).

Submitted abstract:

Galaxy evolution is driven by gas accretion, star formation, and gas outflows from dying stars. We can understand the physics of galaxy evolution by constraining their heavy element abundances. Current studies of distant galaxies utilize “strong-line diagnostics” to determine these abundances. These measurements are not accurate as they are calibrated with nearby galaxies, which differ from galaxies seen in the early universe. One method for solving this problem is to study “R23” and “O32” strong-line diagnostics for distant galaxies and calibrate them to a direct metallicity indicator, [OIII]λ4363. This project analyzes DEEP2 Survey data with the goal of detecting this emission line. We explored different binning approaches to find the best technique to obtain optimal signal-to-noise for stacked spectra. Detections in eight of fourteen composites allow us to calculate average electron temperatures and metallicities. Preliminary results from this project will be presented using regression techniques to relate “R23” and “O32” against metallicity.