Correlation between Compton reflection and X-ray slope in Seyferts and X-ray binaries

We find a very strong correlation between the intrinsic spectral slope in X-rays and the amount of Compton reflection from a cold medium in Seyfert AGNs and in the hard state of X-ray binaries with either black holes or weakly magnetized neutron stars. Objects with soft intrinsic spectra show much stronger reflection than those with hard spectra. We find that, at a given spectral slope, black hole binaries have similar reflection to or more reflection than Seyferts, whereas neutron star binaries in our sample have reflection consistent with that in Seyferts, The existence of the correlation implies a dominant role of the reflecting medium as a source of seed soft photons for thermal Comptonization in the primary X-ray source.