SELF-ABSORBED ACTIVE GALACTIC NUCLEI AND THE COSMIC X-RAY-BACKGROUND

The hard X-ray properties of heavily obscured active galactic nuclei ( AGNs) are investigated. We consider the reprocessing of X-rays by phot oelectric absorption and Compton downscattering in cold material, and compute the transmitted spectra expected for active galaxies. We discu ss the recent OSSE observations in terms of the unified Seyfert scheme , and show that a population of heavily self-absorbed AGNs with an exp onential cutoff at high energies may plausibly explain the cosmic X-ra y background.