'Sub-Eddington, yet mighty: accretion and feedback of bright quasars from Reionisation to Cosmic noon'

The James Webb Space Telescope (JWST) has provided a transformative view of the first quasars and their host galaxies. I will present new JWST/NIRSpec integral field spectroscopy of a sample of quasars at the epoch of Reionization—the most distant quasars known to date. These data reveal powerful nuclear-scale outflows and extended [O III] emission up to ∼7 kpc, tracing large-scale ionized outflows. The associated mass outflow rates are comparable to the star formation rates, suggesting early feedback capable of quenching star formation. I will also introduce a novel, self-consistent method to determine key AGN properties (black hole mass, bolometric luminosity, and Eddington ratio), here applied for the first time on JWST data. This approach shows that super-Eddington accretion represents a short, bursty phase in AGN evolution, while black holes grow for most of their lifetime at an average Eddington ratio of ∼0.1. These results challenge current models of black hole formation and support scenarios involving massive or even primordial black hole seeds.