Late-Time Cosmic Acceleration in Ricci-Gauss-Bonnet Gravity via Gradient Descent Optimization

We study the late-time evolution of the Universe within the f ( R , G ) gravity framework, where R is the Ricci scalar and G is the Gauss-Bonnet term. To make the model tractable, we propose a parametrization scheme and determine its parameters using Gradient Descent, with constraints coming from the latest Cosmic Chronometer (CC) and Pantheon + supernovae data. Key cosmological indicators-the deceleration parameter ( q ) and the equation of state ( ω )-show a clear shift from past deceleration to the present accelerated expansion. Interestingly, the EoS parameter ω remains above the phantom divide, indicating quintessence-like behavior in agreement with current observations. Energy condition assessments reinforce this framework: the strong energy condition is violated, which is consistent with models permitting cosmic acceleration, whereas both the weak and null energy conditions hold true. To check consistency, we also apply the Om( z ) diagnostic, which separates this model from the simple cosmological constant case and highlights its favoring of a quintessence-dominated future. Using the best-fit values, we estimate the age of the Universe, which comes out in close agreement with independent astrophysical measurements. Taken together, the results suggest that f ( R , G ) gravity provides a credible and self-consistent route to explain late-time cosmic acceleration, especially when tested against the combined CC and Pantheon + datasets.