Spectral properties of the Narrow-Line Seyfert 1 Quasar PG1211+143

Abstract

We propose a theoretical model to explain the spectrum of the quasar PG1211+143 emitted in the Optical/X-ray bands. In particular, we suggest that the inner accretion disk may develop a warm, optically thick skin, which produces a profound emission feature observed in the soft X-ray band. This is well modelled with the Comptonized black body emission. The same warm, mildly ionized medium may also be responsible for the hard X-ray reflection and the presence of the iron $K_α$ line. However, in our model it still remains an open question, whether the seed photons for Comptonization come from the cold accretion disc or from the hotter plasma. High resolution spectroscopy available through the Chandra and XMM data may provide now an independent test of the physical conditions in the Comptonizing and reflecting warm skin.