The term Compton reflection is used for a spectral signature observed in EMR from active galactic nuclei (AGNs), indicating a spectrum resulting from Compton scattering of photons from a power-law X-ray source (decreasing with frequency). The term Compton reflection is used for a characteristic "hump" in the observed spectral energy distribution (SED), but the term is also sometimes taken to include emission lines indicating fluorescence of particular elements.
Such power-law spectra (in the X-ray spectral band) generated within AGNs are inferred from their explaining power regarding the observed SED. The Compton reflection is presumed to be generated in a cooler gas cloud near (e.g., immediately in front of) the AGN's internal X-ray source. The presence of iron lines that require absorption of high-energy photons provide more evidence for the model.
Models have been developed regarding mechanisms by which the AGN's black-hole accretion could generate such a power-law spectrum.