VERY HIGH DENSITY CLUMPS AND OUTFLOWING WINDS IN QSO BROAD-LINE REGIONS

摘要

Intercomparison of the spectra of seven high-luminosity quasi-stellar objects (QSOs) shows that there is a gradation of properties in their broad emission-line regions (BELRs) that can be understood as differing mixtures of different gas components. Six of these seven objects have unusually narrow BELR profiles, which greatly facilitates the disentangling of blends and measuring of weak lines. In the QSO 0207 — 398, the BELR is made up of at least three kinematically distinct components; its spectrum is in fact a composite of the spectra of the more homogeneous BELRs in the QSOs at either end of our sequence of properties. This paper focuses on the properties of the line-emitting region in Q0207 —398 dubbed component "A," which has sharp (FWHM = 1000 km s~(-1)), symmetric line profiles centered at zero velocity. We find that these lines are emitted in very dense (n_H ～ 10~(12.5) cm~(-3)) gas at a characteristic radius r ～ 10~(17.7) cm from the continuum source and which emits a low-ionization spectrum including strong Al Ⅲ λ1857. The second component, " B," in Q0207 — 398 is the subject of a companion paper. It is characterized by high-ionization lines such as N Ⅴ λ1240, O Ⅵ λ1034, and C Ⅳ λ1549 with profiles that peak at zero velocity but have a blue tail extending out to —11,000 km s~(-1). It receives about the same incident flux as component A and therefore may lie at the same distance from the continuum source, but it is significantly less dense (n_H ～ 10~(11) cm~(-3)).