The Guerrero Scalar Field as the Source of Cosmological Backreaction: Soliton-Void Contrast and the Emergence of Λ_eff

This work demonstrates that the Guerrero scalar field (φ) — characterized by its soliton structure in galactic halos and its suppression in cosmic voids (the Guerrero Rigidity Filter) — generates a non-negligible cosmological backreaction that contributes to the observed accelerated expansion. Using the Buchert averaging formalism, we show that the extreme density contrast between Guerrero solitons and voids (δ_φ,void ~ -0.995) produces a kinematic backreaction term (Q) that accounts for 20.6% of the observed cosmological constant (Λ). This represents a 1.11x enhancement over standard CDM backreaction models, derived entirely from the physical parameters of the Rigidity Filter without fine-tuning. Key Scientific Contributions:• Quantitative derivation of the Guerrero-Buchert backreaction term Q = 0.206 * (3Ω_Λ).• Prediction of a +24% enhancement in the Integrated Sachs-Wolfe (ISW) amplitude due to deeper cosmic voids, providing a falsifiable signature for Planck and Euclid cross-correlations.• Theoretical framework for Λ as an emergent geometric effect rather than a fundamental constant, designating the remaining ~80% of the acceleration to averaged spatial curvature (⟨R⟩_D) and differential clock rates (Räsänen-Wiltshire effect).