2006ApJ...651L..13D

We report the discovery of hard X-ray delays in the X-ray emission of the Seyfert 1 galaxy Mrk 110, based on a long XMM-Newton observation. Cross-correlation between the X-ray light curves of different energy bands reveals an energy-dependent delay ranging from a few minutes to an hour. We find that the energy spectrum can be modeled by Comptonization of disk blackbody photons. The energy-dependent delay can be modeled as due to the effect of Comptonization in a hot plasma confined within 10 Schwarzschild radii of the black hole. We discuss our results in the context of inverse Comptonization of the soft photons by highly energetic plasma.