Matter under strong gravity

I report on the discovery of high density matter in the immediate vicinity of the central black holes in the Narrow-Line Seyfert 1 Galaxies 1H 0707-495 and IRAS 13224–3809. The density of these clouds is of the order of 10¹⁹cm^-3. The clouds are neutral for Fe and must be embedded into the accretion disc to explain the observations. This results in a partial covering interpretation, where the clouds partially absorb the emission from the accretion disc and part of the emission reaches the observer unabsorbed, leading to a strong soft excess, a sharp Fe K edge without any detectable Fe K reemission. This scenario has been proposed theoretically first by M. Rees in 1987 and appears now to be observationally confirmed with observations of the X-ray observatory XMM-Newton. (author)