SIMBAD references

We present the study of the emission properties of the quasar PG 1211+143, which belongs to the class of narrow line Seyfert 1 galaxies. On the basis of observational data analyzed by us and collected from the literature, we study the temporal and spectral variability of the source in the optical/UV/X-ray bands, and we propose a model that explains the spectrum emitted in this broad energy range. In this model, the intrinsic emission originating in the warm skin of the accretion disk is responsible for the spectral component that is dominant in the softest X-ray range. The shape of reflected spectrum as well as Fe K line detected in hard X-rays require the reflecting medium to be mildly ionized (ξ∼500). We identify this reflector with the warm skin of the disk, and we show that the heating of the skin is consistent with the classical αP_tot prescription, while αP_gas option is at least 2 orders of magnitude too low to provide the required heating. We find that the mass of the central black hole is relatively small (M_BH∼10⁷-10⁸ M_☉), which is consistent with the broad line region mapping results and characteristic for NLS1 class.