Observational constraints on a spinor field generalized Chaplygin gas model in a spherically symmetric FLRW spacetime

Abstract Despite the remarkable success of the standard Λ CDM model in describing the evolution of the universe, several unresolved issues remain, such as the true nature of dark energy, fine-tuning problems, and the persistent Hubble tension. Motivated by these shortcomings, we construct a spinor field-based Generalized Chaplygin Gas (GCG) model that unifies dark matter and dark energy within a spherically symmetric Friedmann Lemaître Robertson Walker (FLRW) spacetime. This framework incorporates a nonlinear spinor field and considers an open universe geometry. We constrain the model parameters using the latest observational datasets, including Type Ia supernovae from the binned Pantheon compilation, Hubble parameter measurements from cosmic chronometers (CC) and SDSS, including baryon acoustic oscillation (BAO) data. Employing Markov chain Monte Carlo (MCMC) sampling techniques, we obtain best-fit values that indicate the spinor GCG model provides a competitive and viable alternative to the Λ CDM, particularly in the late-time universe. Furthermore, the model predicts a lower present-day Hubble constant, offering a potential resolution to the Hubble tension. The results highlight the rich phenomenology of spinor fields and their possible role in the dynamics of dark energy through spacetime interaction.