| Abstract: Supermassive black holes can be ejected from their host galaxies via gravitational-wave recoil or multi-body interactions. These Runaway Supermassive Blackholes (RSMBHs) travel through the circumgalactic medium (CGM) at supersonic velocities (v>1000 km/s), producing characteristic bow shock structures with complex kinematic signatures. Recent JWST observation of a 62 kpc linear feature RBH-1 at z = 0.96 (van Dokkum et al., 2025) reveal steep velocity gradients (about 600 km/s over 1 kpc) which are consistent with turbulent mixing of shocked gas with CGM through turbulent entrainment, a phenomenon demanding detailed theoretical characterization. While analytical models of bow shock structure provide qualitative interpretation of these observations, detailed hydrodynamical simulations are needed to connect observational signatures to the underlying physics of shock propagation and radiative cooling in the CGM. Notably, there is a severe scarcity of three-dimensional hydrodynamical simulations of RSMBH systems in the literature; existing theoretical work relies primarily on analytical approximations or simplified models that do not fully capture the interplay between shock dynamics, radiative cooling, and post-shock gas evolution at scales relevant to observations. We present three-dimensional hydrodynamical simulations using AthenaK code with radiative cooling to model bow shock kinematics, post-shock gas dynamics, and mass entrainment mechanisms in RSMBH systems. Our simulations examine shock geometry, velocity structure and the role of radiative cooling in post-shock thermodynamics. By systematically varying RSMBH mass, velocity, and CGM density, we establish scaling relations between RSMBH properties, bow shock morphology, kinematic signatures, and filament mass production. Our simulations provide quantitative predictions for shock velocity measurements, velocity gradients, and cooling signatures observables constraining the impact of runaway SMBH events in galaxy evolution. |
