Seminario DAS: To Metallicity and Beyond: measuring accurate elemental abundance(s) at Cosmic Noon

Speaker: Ryan Trainor
Affiliation: Franklin & Marshall College

Abstract: The “metallicity” of a galaxy—i.e., the total mass fraction of heavy elements—is a key tracer of the complex interactions of stars, gas, and black holes that regulate galaxy evolution. As such, measuring galaxy metallicities is a major goal of current galaxy surveys from the local Universe to the epoch of reionization. However, galaxy metallicities in the early Universe are challenging to measure and interpret for two reasons. Firstly, local calibrations for metallicity measurements from strong emission lines are inconsistent at high redshifts, requiring new calibrations established in situ. Secondly, the relative abundances of different elements vary widely with star-formation history and produce disparate observational effects, which means that “metallicity” as a single parameter is insufficient to characterize the chemical enrichment of forming galaxies. I will present new results from the CECILIA and KBSS surveys, which are using galaxy spectra from JWST/NIRSpec and Keck/LRIS+MOSFIRE to constrain individual elemental abundances in galaxies at Cosmic Noon (z ~ 2-3), while also aiming to establish new methods for elemental abundance measurements that can be applied to current and future galaxy surveys.