Column density (cm^-2) slice of simulation A at t = t_ff. The colors represent the column density along the line of sight to the black hole, which is located at the upper left side (the black arrows indicate the direction of radiation). The density is shown in black contours. Contour levels are 1, 4, 16, 64, 256, 1024  × 10⁴ cm^-3. The white spheres display the location of the sink particles and the red arrow indicates the direction of the cloud’s orbital motion.