Speaker
Description
The origin of the first galaxies and supermassive black holes (SMBHs) remains an open question in cosmology, particularly in light of recent JWST discoveries of massive galaxies and SMBHs at high redshift. We investigate the role of heavy primordial black holes (PBHs), with masses $\sim 10^6$-$10^7\,M_{\odot}$ and constituting a small fraction of dark matter (DM), as potential SMBH seeds and their impact on cosmic structure formation. We employ high-resolution N-body and hydrodynamical simulations using the GIZMO code, alongside semi-analytical models, to explore the effects of heavy PBHs across cosmic history. N-body results demonstrate that PBHs accelerate massive halo formation, disrupting hierarchical structure formation by attracting and engulfing nearby halos, potentially leading to a bimodal halo mass function. Hydrodynamical simulations further show that early star formation is strongly modified by the initial density perturbations and accretion feedback from such massive PBHs at very high redshifts, suppressing stellar assembly while maintaining low metallicities in compact systems. Our results suggest that PBH-seeded halos can naturally produce BH-dominated, metal-poor galaxies, providing a viable explanation for early SMBHs such as Abell 2744–QSO1 and The Cliff. Future observations with JWST, Roman, and LISA will be critical for distinguishing PBH-driven structure formation from standard $\Lambda$CDM scenarios.
