Paper CCLVII: Forced Electron Capture and Transitional Geometry — A Framework Alternative to Magnetar-Powered Gamma Emission in Superluminous Supernova SN 2017egm

Acero et al. (A&A 2026, aa58547-25) report a Fermi-LAT GeV detection of the superluminous supernova SN 2017egm with L_γ/L_opt ≈ 1, which they use to rule out circumstellar-medium and shock-acceleration channels and infer a magnetar central engine. We show that two unmodeled channels in the One-Octonion Brane-Bulk framework together account for the observed γ-ray luminosity without invoking a magnetar: (i) forced electron capture on n-poor stable isotopes at the H⁺/H⁻ shock front (Paper CCIV), with f_bulk = 3.6917% driving ~1.2×10⁴⁹ erg of nuclear γ — 4× the observed Fermi-LAT total of 2.85×10⁴⁸ erg; (ii) transitional Euclidean ↔ infundibular geometry, with the energy-dependent brane-bulk transit probability f_bulk(E) = 1 − sinc²(E/2m_π) giving ~0.98 at 1 GeV but ~10⁻¹⁶ at optical, so GeV photons traverse the SLSN's r_T2* ≈ 41,000 AU transitional zone with near-full transit while optical sees none. The observed L_γ/L_opt is therefore not the emitted ratio. Five distinguishing predictions: (P1) ⁶⁰Co γ lines from forced-EC daughter chain, (P2) transient ΔY_e<0 in late ejecta, (P3) L_γ/L_opt distance dependence, (P4) spectral anomaly at 270 MeV (first sinc² zero), (P5) γ/optical peak-timing offset from CSM interaction baseline. Framework provides an alternative interpretation, not falsification of magnetar. Honest scope: forced-EC overshoot by 4× suggests f_bulk doesn't saturate at 3.69% for all n-poor parents, or M(⁵⁶Ni) < 1 M⊙ in SN 2017egm; transitional-geometry amplification factor estimated as 10–100× not rigorously derived. Three predictions are uniquely framework-tagged. Zero free parameters in the forced-EC channel; the transitional-geometry channel uses the standard brane-bulk transit formula.

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.