Supermassive primordial black holes for the GHZ9 and UHZ1 observed by the JWST

Abstract: The high redshift ($z>10$) galaxies GHZ9 and UHZ1 observed by the James Webb Space Telescope (JWST) are very massive and have exceptionally high black hole-to-star mass ratios with the central black hole masses $M\gtrsim 10^7\rm~M_\odot$. In this paper, we explore the possibility that they are seeded by the supermassive primordial black holes (SMPBHs), which came into being in the very early universe, with initial masses $\sim 10^7\rm~M_\odot$. We present the self-similar accretion solutions for SMPBHs, and find that the mass growth of SMPBHs during pregalactic era may be negligible. These SMPBHs, when the redshift $z\lesssim 20$, can accelerate seeding high-redshift galaxies and their baryonic content, and consequently explain the central supermassive black holes (SMBHs) of high-redshift massive galaxies through sub-Eddington accretion. According to our results, SMPBHs actually could lead to the existence of more massive SMBHs at higher redshifts compared to other SMBH seed scenarios, specially SMBHs with masses $M\gtrsim 10^7~\rm M_\odot$ at $z>20$ might only origin from SMPBHs, thus the corresponding observation can serve as a potential probe to PBHs.