The first two-year results of JWST have unveiled an unexpectedly large number of accreting black holes in the early Universe. Unlike the general populations of super massive black holes at the low redshifts, these early black holes exhibit distinctly different properties. They appear over-massive compared to the stellar content of their host galaxies, generally show non-detection in the hard X-ray band and radio bands, and even show non-variability in the rest frame optical. This new AGN population revealed by JWST challenges the previous paradigm of the seeding and growth of supermassive black holes. It also raises a debate on whether JWST is selecting real accreting black holes or not. I will give an overview of the current observational results on the high-z AGN mainly based on observations from the GTO programs JADES and GA-NIFS. With the current observational evidence, we might need to reevaluate the picture of “a standard AGN” established in the pre-JWST era and consider new models for the growth environments and accretion physics at early times, including dense nuclear gas obscuration and/or supper-Eddington accretion.
BIO
Xihan Ji is currently a postdoc at Cavendish Lab and Kavli Institute for Cosmology at the University of Cambridge. He received his PhD in 2023 from the University of Kentucky. His research interests include chemical evolution of galaxies throughout the cosmic time and modeling of the warm ionized gas in galaxies and AGN. Specifically, his recent works focus on chemical abundances of nitrogen-enhanced galaxies/AGN and nuclear environments of low-luminosity AGN at high redshift. He is actively involved in the JWST program JADES and the upcoming local-volume survey AMASE.
Host: Junkai Zhang
