Affiliation: European Southern Observatory (ESO)

Contribution: Oral

Title: Charting the chemical evolution of galaxies across cosmic time with deep JWST observations

Abstract: I will discuss the emerging picture on the evolution of the ISM and chemical enrichment properties of early galaxies in the context of the first two years of JWST observations. Exploiting deep spectroscopy of thousands of galaxies from the JADES-GTO survey, it is possible to characterise the evolution in the metallicity scaling relations at z~3-10, setting powerful constraints on the star formation history of early galaxies, their gas reservoirs, and the impact of star-formation-driven outflows. I will also present a detailed analysis of the rest-frame UV and optical spectra of a z~9.4 galaxy (a.k.a. GS-z9) exploiting ‘ultra-deep’ (> 150 hours combining observations in both prism and medium resolution gratings). This source is characterised by a steeply rising star formation history which is reflected in the inferred young stellar age, high star-formation rate surface density, high ionisation parameter, low metallicity, and low C/O abundance; the latter, coupled with relatively high nitrogen enrichment, possibly reveals the chemical enrichment signatures of very massive stars progenitors. Finally, I will present results from ‘Measuring Abundances at high Redshift with the Te Approach’ (PI Curti), a deep (33 hours in G140M/F100LP + 7 hours in G235M/F170LP + 3 hours in G235H/F170LP) GO NIRSpec/MSA programme providing high S/N spectra with simultaneous detections of multiple (strong and faint) rest-frame optical emission lines in individual galaxies (including temperature-sensitive auroral lines like [O III]4363, [O II]7320,30, and [S III]6312, as well as high order Balmer lines), allowing to characterise in detail temperature-temperature relations, chemical abundance patterns, ionisation conditions, gas density, and dust attenuation in z~2-3 sources. I will also try to interpret these spectra in the framework of novel, multi-cloud photoionisation models which simultaneously reproduce all the observed emission lines, discussing the implications on the metallicity derivation based on the “standard” Te-method and strong-line diagnostics.

This contribution can be found here (pdf).