Akademik Veri Yönetim Sistemi
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS, 2026 (SCI-Expanded, Scopus)
We investigate a thermodynamically consistent unification of the late-time dark sector in a model-independent effective-fluid framework endowed with causal Israel-Stewart (IS) bulk viscosity. On a flat FLRW background, we recast the dynamics into a closed autonomous system, identify stable scaling solutions that alleviate the coincidence problem, and recover a smooth Lambda CDM limit. We compute background observables E(z), q(z) and j(z) and adopt a phenomenological quasi-static closure for linear growth via (mu(a,k),eta(a,k)) without committing to a specific modified-gravity microphysics. Physical consistency is ensured by positive entropy production and IS causality bounds (0 < c(b)(2) <= 1). The validity of the truncated-IS regime is quantified through & varepsilon;(IS)(z) << 1 over the redshift range considered, and we display & varepsilon;(IS)(z) along fiducial trajectories. We also document a prospective SNIa/BAO/RSD/cosmic-chronometer pipeline (priors, likelihood structure, AIC/BIC) intended for follow-up work; no posterior constraints are claimed here. The framework yields falsifiable background signatures mild deviations in E(z) and characteristic trends in q(z) and j(z) and remains compatible with luminal gravitational-wave propagation constraints. It provides a clean baseline for subsequent data-driven tests and for embedding explicit geometric models should one wish to move beyond the effective-fluid level.