A Localized Late-Time Interaction in the Dark Sector

This work investigates a phenomenological cosmological model in which an interaction between cold dark matter and dark energy is activated during the late cosmological epoch. The interaction is modulated by a smooth sensor-like function peaking at z≈0.5. For interaction strengths x≤0.2 the model remains compatible with current BAO and supernova constraints while producing a mild suppression of late-time structure growth, potentially alleviating the S8 tension.