LAM seminar by Guido Roberts-Borsani: « Between the extremes: JWST insights into the physics of the first stars, galaxies, and black holes »

Title: Between the extremes: JWST insights into the physics of the first stars, galaxies, and black holes

Abstract:

The emergence of the first sources ~13.6 billion years ago had a profound effect on the Universe, initiating its last major phase-change and ending the so-called cosmic Dark Ages. Unlocking the physics of those primordial sources thus represents a fundamental step towards a comprehensive understanding of the initial conditions that formed the building blocks for the Universe we see today. While Hubble painted a fairly straight forward picture, early JWST data revealed an infant Universe far more remarkable and exotic than previously thought, with hyper-luminous galaxies detected out to z~14, chemically-enriched interstellar media and peculiar elemental abundances out to z~12, and apparently over-massive black holes to z~10. Are these sources representative of the global population, or do they reflect peculiar objects at a particular evolutionary phase? In this talk, I will present efforts to address these questions through the spectroscopic study of statistical samples of high-redshift (z>5-14) galaxies with JWST/NIRSpec, establishing a benchmark for their chemical enrichment journeys, ISM conditions, (re)ionizing capabilities, and spectroscopic fingerprints. Additionally, I will showcase the importance of utilizing unbiased samples of galaxies to gain representative insight into the ISM conditions and evolutionary pathways of the most luminous populations uncovered by JWST.