Seminar by David Setton, Princeton
The unprecedented infrared sensitivity of the James Webb Space Telescope promised to reveal the earliest stages of the formation of massive galaxies, long theorized but never directly observed. In the first three years of its operation, it has over-delivered on that promise. Deep JWST observations have uncovered an abundant population of massive galaxies at z>3 that appear to have formed earlier than expected in cosmological simulations, and a mysterious population of "Little Red Dots" at even higher redshift that were first interpreted as the dusty, star forming cores of these early-forming massive galaxies. I will demonstrate how we worked to build up the panchromatic spectral energy distributions of Little Red Dots to definitively show that they are not dusty massive galaxies, not dusty active galactic nuclei, and perhaps instead a never-before-seen phase of early supermassive black hole growth. I will then return to the massive galaxy population at high-z and offer a way forward toward understanding their formation channel by studying their direct progenitors--post-starburst galaxies--across cosmic time.
Host: Timothy Halpin-Healy