| Abstract: Active Galactic Nuclei (AGN) jets are powerful drivers of feedback, transporting energy from the central supermassive black hole into the host galaxy and beyond. Through their interaction with the interstellar and circumgalactic medium (ISM/CGM), jets regulate gas thermodynamics and galaxy evolution. While jet dynamics are often modeled as adiabatic, growing observational and numerical evidence indicates that radiative cooling plays a crucial role in governing jet–environment interactions, particularly on kiloparsec scales where jets encounter a dense, multiphase ISM.
As AGN jets propagate, they inflate an over-pressured cocoon that collimates the initially conical outflow and mediates energy transfer to the surrounding medium. Radiative cooling in shocked ISM, shocked jet material, and mixed-phase gas can significantly reduce cocoon pressure. In these dense regions, cooling times can be extremely short, enabling rapid thermal energy losses that may lead to cocoon collapse, jet decollimation, and reduced coupling efficiency between the jet and the ambient.
We present high-resolution hydrodynamic simulations of AGN jets interacting with a realistic multiphase ISM and transitioning into the CGM, incorporating a tabulated radiative cooling function. We study both uniform and vertically stratified ambient media to assess how environmental structure influences jet evolution. In uniform media, shocked diffuse gas and mixed jet–cloud material cool efficiently, leading to strong radiative losses from the cocoon. In contrast, in stratified atmospheres the jet expands into lower-density CGM regions on timescales shorter than the local cooling time, substantially reducing radiative losses and allowing the cocoon to retain higher pressure.
By varying jet power, opening angle, tilt, and ISM clump properties, we examine how radiative cooling and environmental stratification together regulate cocoon pressure, jet morphology, and the overall efficiency of AGN feedback. These results provide new constraints on when AGN jets break out of dense galactic environments versus when radiative losses limit their impact on galaxy evolution.
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