Event Details

The emission-line spectrum of a galaxy encodes information about many interesting galaxy properties. Extracting physically-meaningful properties (e.g., star-formation rate, dust reddening, metallicity, gas ionization state, ionizing source) from observed emission-line strengths and line ratios requires the use of diagnostics that are calibrated in the local universe. Observations of high-redshift galaxies suggest that some of these diagnostics evolve with redshift and must be revised in order to provide robust estimates of high-redshift galaxy properties. I will give an overview of the MOSFIRE Deep Evolution Field (MOSDEF) survey, in which we obtained rest-optical emission-line measurements of >1000 galaxies at z~1.5-3.5. Using data from the MOSDEF survey, I will summarize the evolution of galaxy emission-line properties from z~0 to z~3 and discuss the uncertainties affecting the interpretation of emission lines at z>1, particularly focusing on the ability to determine gas-phase metallicity. Despite the remaining uncertainties, progress is being made towards understanding the scaling between metallicity and global galaxy properties such as stellar mass and star-formation rate. The form and evolution of these metallicity scaling relations provide valuable insight into gas accretion, feedback, and galaxy growth throughout cosmic history. Independent metallicity measurements based on temperaturesensitive auroral emission lines present an avenue to reassess metallicity calibrations at high redshift. I will present detections of these temperature-sensitive auroral lines at z>2, and discuss the prospects of obtaining a statistical sample of z>1 galaxies with temperature-based metallicities using current and future facilities. Such measurements can pave the way for robust galaxy metallicities at high redshifts.

Video Recording