Colloquium – Dale Kocevski

Dale Kocevski, Colby College

Insights into Early SMBH Growth from JWST.

The capabilities of JWST are now allowing us to measure the host demographics of AGN beyond cosmic noon and detect lower luminosity quasars out to the epoch of reionization. I will discuss recent AGN-related results from the CEERS Survey and what they tell us about the growth of SMBHs in the early universe. This includes the discovery of an actively accreting SMBH at z=8.67, which is one of the most distant AGN ever discovered. The mass of the black hole and its extreme redshift place tight constraints on its formation and subsequent growth. I will also discuss the discovery of multiple low-luminosity, broad-line AGN at z>5 found with our NIRSpec observations. These sources are powered by black holes with masses of order 10^7 Msol, making them the least-massive BHs known in the early universe. We derive host stellar masses for each AGN, allowing us to place constraints on the BH-galaxy mass relationship in the lowest mass range yet probed in the early universe. Studies in this low-mass regime are key to constraining models of BH seeding and the early growth history of SMBHs. Finally, I will discuss the host properties of X-ray bright AGN at 3<z<5, which we find to be located in massive, quiescent galaxies with undisturbed morphologies. The presence of AGN in passively evolving galaxies at z>3 is significant because a rapid feedback mechanism is required in most models and simulations to explain the growing population of massive quiescent galaxies observed at these redshifts. I will discuss the implications of these findings and what they tell us about the connection between SMBH growth and the emergence of the first generation of massive quiescent galaxies in the early universe.

Feb 22, 2024 @ 4:00pm Central in Stevenson 4327; reception beforehand at 3:30pm in Stevenson 6333

Host: J Runnoe