International Journal of Science and Technology (IJST)

Time Evolution of Cosmological Parameters in an FLRW Universe with an Empirical Dynamical Cosmological Term

The accelerated expansion of the Universe has motivated the study of dynamical cosmological models with a time-dependent cosmological term. In this work, we investigate the evolution of important cosmological parameters in a spatially flat Friedmann–Lemaitre–Robertson–Walker (FLRW) Universe by introducing an empirical dynamical cosmological term expressed in terms of the Hubble parameter and its time derivative. Assuming a barotropic equation of state for the cosmic fluid, analytical expressions are obtained for the scale factor, Hubble parameter, deceleration parameter, energy density, gravitational constant, and cosmological term. Model parameters are constrained using the physical requirements of an expanding Universe, a decreasing Hubble parameter, and a transition from decelerated to accelerated expansion. The model predicts continuous expansion, a decreasing energy density, and a positive cosmological term that gradually decays with time. The gravitational constant also exhibits a time-dependent evolution, and its predicted present rate of change is consistent with previously reported observational limits. These results indicate that the proposed empirical dynamical cosmological term provides a physically viable framework for describing the evolution of the expanding Universe.