Monsters in the Dark: Searching Far and Wide for Ultra-Luminous Galaxies at Cosmic Dawn

Connection information: https://science.nasa.gov/astrophysics/programs/cosmic-origins/community/galaxies-sig-seminar-4-february-2026/

Speaker | John Weaver

Abstract:

The first galaxies (z > 10) appear to have formed faster and more efficiently than predicted by standard models, but they are difficult to study and few in number. Studying the brightest analogues at more accessible redshifts (z ~ 7 – 9) is the next best option. I will present the most luminous galaxies yet identified in the epoch of reionization (MUV = –24), 10 times brighter than GNz-11. Unearthed from 50 deg² of Euclid's Deep Fields, these exceptionally rare and luminous galaxies present the first constraints on the very tip of the UV LF where currently degenerate models can finally be tested. I will preview these systems by presenting the morphologies, assembly histories, and spatially-resolved properties of one of the most luminous z ~ 8 galaxies observed by NIRSpec/IFU. I will show how these results underscore the need for spatially-resolved spectroscopy to accurately interpret the thousands of these remarkable galaxies that will be discovered by Euclid and Roman.

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