Comptonization of the Lyman edge in active galactic nuclei

Recent X-ray observations indicate the presence of both relativistic particles and cold gas very close to the center of active galactic nuclei. However, the UV radiation from this cold gas does not exhibit the Lyman edge predicted by many accretion disc models. Here we show that Comptonization of the intrinsic spectrum by gas in the form of a hot corona at the intermediate temperatures $$(T\sim {10}^{8}\,\text{K})$$ can efficiently smear out the Lyman edge without destroying the observed iron K-fluorescent line.