3D moving-mesh hydrodynamical simulations of wind-/jet-driven ultraluminous X-ray source bubbles

Abstract We perform 3D moving-mesh hydrodynamical simulations of bubble nebulae around ultraluminous X-ray sources, using the state-of-the-art software AREPO. We use a Monte Carlo method to inject outflows with uniform mass outflow rate and momentum, in a conical funnel with a specific half opening angle. Simulation results show that the morphology of the bubble is determined by the initial momentum of the outflows, while the mechanical power of the outflows only influences the size of the bubble without changing its shape. Low mechanical power also results in a short cooling timescale of the system, leading to early collapse of the bubble shell. The half opening angle of the outflows and the viewing angle of the system determine the observed bubble eccentricity together. Compared with the observational morphology of the ULX bubble sources NGC 55 ULX-1 and NGC 1313 X-2, our simulation favors the fact that the high-velocity outflows of the accretion disks in these two systems are confined in a narrow funnel region.