Title: Stellar mass assembly of massive galaxies in the first five billion years of the Universe

Abstract:Over the past two decades, extensive multi-wavelength observations of the COSMOS field have provided an exceptional view of galaxy evolution across cosmic time. With the recent addition of JWST/NIRCam imaging, our understanding of the distant Universe has advanced dramatically. We can now investigate the physical properties and morphologies of massive galaxies at cosmic noon with unprecedented detail and extend these studies back to the primordial Universe.

After introducing the broader context of galaxy formation and evolution, I will present the confirmation for a population of unexpectedly bright galaxies already in place at z>10, i.e.  less than 500 million years of cosmic time. These sources challenge standard models of early galaxy formation. While several explanations have been already suggested, our clustering measurements support a scenario in which star-formation efficiency was significantly elevated in the young Universe.

In the second part of the talk, I will present new results connecting star‑formation histories, morphology, and environment for galaxies at cosmic noon 1 < z < 3. These findings establish solid links between these key aspects of galaxy evolution, and shed new light on the emergence of the massive and quenched elliptical galaxies.