Speaker
Description
The James Webb Space Telescope (JWST) has seen an excess of massive bright galaxies at Cosmic Dawn. A significant fraction of these galaxies have evidence of active galactic nuclei (AGN), implying that their supermassive black holes (SMBHs) underwent rapid growth, but the evolutionary pathway for this growth remains unclear. We investigate SMBH growth in this context using zoom-in cosmological hydrodynamic simulations with the adaptive mesh refinement code RAMSES at an effective resolution of ~10 pc. By z = 9, the galaxy resides in a 10^11 Msol halo with a stellar mass of 10^9 Msol. In a series of numerical experiments, we study the interplay between the SMBH and the host galaxy by varying the SMBH accretion rate, AGN feedback efficiency, and SMBH seed mass. We find observed BH-to-stellar mass ratios are best reproduced by a simulation with a 10^4 Msol BH seed mass, super-Eddington accretion, and moderate AGN feedback efficiency (15%). We present an analytical explanation for this finding by comparing characteristic growth rates of the galactic halo and the SMBH in and outside of the self-regulated regime.