Self-interacting dark matter model seeds early supermassive black holes explaining Little Red Dot abundance

The paper applies a relativistic non-equilibrium halo evolution code to track SIDM cores from initial collapse through heat conduction-driven inflow. In highly concentrated pre-reionization halos the model produces black hole seeds within a few hundred Myr then sustains prolonged dark-matter accretion that reaches supermassive scales without requiring baryonic fuel or mergers. This pathway yields an SMBH population whose space density and redshift distribution align with JWST LRD statistics while predicting undermassive stellar hosts.

Standard baryonic seeding scenarios struggle with the extreme BH-to-stellar mass ratios and early emergence of LRDs. The SIDM channel bypasses these tensions by decoupling seed formation and growth from galaxy assembly. The required halo concentration and merger-avoidance probability naturally limit the predicted LRD fraction, offering a built-in explanation for their observed rarity.

Because the work is a theoretical simulation study with no direct observational validation, the key limitation is the assumed SIDM cross-section and initial halo profiles. Stronger evidence would require either direct detection of SIDM signatures in dwarf galaxies or JWST spectroscopy confirming the predicted dark-matter-dominated accretion flows around LRDs.