Seeding mechanism of massive black holes at high redshift

Determine the seeding mechanism(s) of massive black holes at high redshift that can explain the presence of ~10^7–10^8 solar-mass black holes by redshift z≈4–6 in compact galaxies identified as Little Red Dots, consistent with current JWST and related observations.

Background

Observations with JWST reveal a population of compact, high-redshift systems (Little Red Dots) that likely host massive black holes with masses up to 10^7–10^8 solar masses by z~4–6, and possibly as early as z~10. Multiple theoretical pathways have been proposed for forming the initial seeds, including runaway stellar collisions in dense clusters, direct collapse of gas, or other channels, but their relative contributions remain uncertain.

The paper develops a semi-analytical framework in which nuclear star clusters evolve and can grow central black holes through tidal disruption events, captures of stellar-mass black holes, and gas accretion. Despite modeling growth from plausible initial conditions, identifying and constraining the initial seeding channel(s) is explicitly noted as unresolved.