Séminaire/Seminar Galaxies |
| « From Little Red Dots to Lya Emitters: JWST Insights into the Early Universe » |
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Roberta Tripodi |
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Recent observations with the James Webb Space Telescope (JWST) are transforming our understanding of galaxy formation and supermassive black hole (SMBH) growth in the early Universe. Among its most intriguing discoveries is a new population of compact, red, high-redshift sources known as Little Red Dots (LRDs), which may trace the earliest phases of SMBH assembly, although their physical nature remains poorly understood. At the same time, JWST is enabling population-level studies of early star-forming galaxies that shaped the reionization era, moving beyond analyses of individual objects.
In this talk, I will present JWST imaging and spectroscopic results for two LRDs, showing that some host rapidly accreting SMBHs with extreme properties, including low metallicity, strong broad emission lines, stratified broad-line regions, and black hole masses that appear overgrown relative to their host galaxies. I will also discuss ongoing work on Lya-emitting galaxies at z > 4 based on stacked spectroscopic observations, which reveal young, intensely star-forming systems characterized by steep UV slopes, strong optical emission lines, and low dust attenuation. Together, these results provide new constraints on the physical processes governing star formation, radiation escape, and black hole growth in the early Universe, and link individual extreme objects such as LRDs to the broader population of early galaxies. |
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jeudi 19 mars 2026 - 11:30 Salle Entresol Daniel Chalonge Institut d'Astrophysique de Paris |
| Page web du séminaire / Seminar's webpage |