• black hole physics;
  • galaxies: active;
  • X-rays: galaxies


An exploration of the relationship between bolometric luminosity and outflow velocity for two classes of X-ray outflows in a large sample of active galactic nuclei has been performed. We find that line radiation pressure could be one physical mechanism that might accelerate the gas we observe in warm absorber, v∼ 100–1000 km s−1, and on comparable but less stringent grounds the ultrafast outflows, v∼ 0.03–0.3c. If comparable with the escape velocity of the system, the first is naturally located at distances of the dusty torus, ≈1 pc, and the second at subparsec scales, ≈0.01 pc, in accordance with large set of observational evidence existing in the literature. The presentation of this relationship might give us key clues for our understanding of the different physical mechanisms acting in the centre of galaxies, the feedback process and its impact on the evolution of the host galaxy.