Density-Triggered Gravitational Transport and the Rapid Formation of Supermassive Black Hole Seeds

Observations of quasars at redshifts z ≥ 6 imply the existence of supermassive black holes (SMBHs) with masses M_BH ∼ 10^9 M_⊙ less than one billion years after the Big Bang. Explaining the rapid assembly of such objects remains a fundamental challenge. Heavy black hole seed models—such as direct collapse black holes, supermassive stars, and quasi-stars—alleviate the growth problem by postulating seed masses of 10^4 – 10^6 M_⊙, but typically assume the suppression of fragmentation and the presence of sustained high inflow rates without specifying a physical origin.We propose a new framework in which heavy black hole seeds arise from a density-triggered modification of effective gravitational transport in collapsing primordial gas. Rather than altering gravity at cosmological or galactic scales, our model introduces an environment-dependent enhancement of angular momentum redistribution that activates only in dense proto-galactic environments. This mechanism suppresses fragmentation and enables coherent, monolithic inflow at rates Ḿ ∼ ρ^{3/2}_G, naturally assembling massive seeds on Myr timescales.We develop a minimal analytic model linking halo thermodynamics, transport efficiency, inflow rate, seed mass, and subsequent Eddington-limited growth. We show that seeds of mass M_seed ≥ 10^4 M_⊙ forming at z ∼ 20 can grow into the observed z ∼ 7 quasars without requiring super-Eddington accretion or extreme radiative backgrounds. The model recovers standard direct-collapse scenarios as a limiting case while providing a physical explanation for why only a subset of early halos enter a monolithic collapse regime.We outline observational signatures that distinguish this mechanism from conventional heavy-seed models, including elevated early M_BH / M_* ratios, characteristic gravitational-wave merger mass distributions, and host halo biases at high redshift.