Infrared tracers to study the chemical evolution of galaxies – J. A. Fernández-Ontiveros

https://geco2023-1gyr.sciencesconf.org/

Shedding new light on the first billion years of the Universe
16th edition of the GECO team conference cycle
3-7 Jul 2023 Marseille (France)

Title: Infrared tracers to study the chemical evolution of galaxies

Abstract: IR-based abundance measurements are essential to understand the evolution of galaxies, since most of the star formation activity -and therefore the production of heavy elements- occurs in deeply dust-embedded regions. Complete abundances can be provided by nebular lines in the rest-frame mid- to far-IR range, using extinction-free and temperature-insensitive diagnostics, two major advantages over optical tracers. We present Hii-Chi-Mistry-IR (Hcm-IR), a new method for obtaining IR-based metallicities from a Bayesian calculation over a grid of photo-ionisation models that cover a wide range in O/H, N/O, and ionisation parameter. The code performance is tested against three different galaxy samples covering a wide range in metallicity, 7.2 ≲ 12 + log(O/H) ≲ 8.9, with available IR spectroscopy from Spitzer, Herschel and SOFIA. Specifically, observations of the [NIII]57µm and [OIII]52,88µm lines are essential to determine the N/O abundance, which is key to constraining chemical evolution models. We applied the code to a small sample of distant galaxies located at 1.8 ≲ z ≲ 7.5 with ground-based detections of the far-IR lines redshifted in the submm range, revealing sub-solar N/O and O/H abundances. Finally, I will discuss how IR-based tracers can be used to address the main open questions on the chemical evolution of galaxies. The script to derive chemical abundances with HCm-IR is publicly available at https://home.iaa.csic.es/~epm/HII-CHI-mistry-IR.html.