Generalized Second Law of Thermodynamics and Dynamical System Analysis of Modified Holographic Dark Energy in f(Q) Gravity

Abstract

We investigate the late-time cosmic evolution of a spatially flat Friedmann–Robertson–Walker universe filled with pressureless matter and modified holographic dark energy within the framework of symmetric teleparallel f(Q)gravity. The corresponding modified Friedmann equations are derived, and the validity of the Generalized Second Law of Thermodynamics (GSLT) is examined on both the apparent and event horizons, explicitly incorporating non-equilibrium entropy production effects. By recasting the cosmological field equations into an autonomous dynamical system, the stability and physical viability of the critical points are analyzed in detail. Our results reveal a strong correspondence between stable accelerated attractor solutions and the attainment of thermodynamic equilibrium, indicating the thermodynamic consistency of the modified holographic dark energy scenario in f(Q)gravity.