LRDs at z = 4–8 are proto-sump focal zones. Star formation efficiency ηSF = R1/2/(1 + R1/2) where R = MBH/Msump. This is physical for all R > 0: ηSF ∈0, 1. Peak occurs asymptotically at R →∞(ηSF →1); half-efficiency at R = 1. LRD transition zLRD ≈4.5 for MBH ∼108 M⊙. v2 correction: original ηSF = 1 −R−1/2 gives negative values for R < 1 (unphysical). Part of the One-Octonion Brane-Bulk Framework series. Anchor DOI: 10.5281/zenodo.19120873. Community: one-octonion-brane-bulk. Author: Bharathi Dasan Jagadeesan, M.D., University of Minnesota. ORCID: 0000-0002-1143-941X.
Bharathi Jagadeesan (Sat,) studied this question.