Impact of Kaon Condensation on the Thermal Evolution of the CCO in HESS J1731--347 Supernova Remnant

Recent analyses of the central compact object in the HESS J1731--347 supernova remnant suggest an unusual combination of a low mass and small radius, while its thermal emission indicates a relatively high surface temperature at its estimated age. Reconciling these structural and thermal properties within a unified theoretical framework may provide important constraints on the equation of state and composition of dense matter. In this work, we investigate the thermal consequences of negatively charged kaon condensation, an exotic phase that softens the equation of state and facilitate the reproduction of the inferred bulk properties of HESS J1731--347. We find that the onset of kaon condensation strongly accelerates the thermal evolution, leading to surface temperature substantially below the observationally inferred range. Within the adopted cooling framework, kaon condensation therefore cannot simultaneously account for the structural and thermal properties of HESS J1731--347.