Broad Emission and Absorption Line Outflows in the Quasar SDSS J163345.22+512748.4

Abstract

Abstract We present a detailed study of the optical and near-infrared (NIR) emission and absorption line spectrum of the quasar SDSS J163345.22+512748.4. We discovered on the newly acquired NIR spectrum a highly metastable neutral helium broad absorption line (BAL) He i* λ10830 with a width of ∼2000 km s−1 and a blueshift of ∼7000 km s−1 in the velocity space. The BAL system is also significantly detected in Mg ii and He i* λ3889. We estimate a column density of (5.0 ± 1.7) × 1014 cm−2 for the He i*(2 3S) level and infer an ionization parameter of U A  = 10−1.9±0.2 for the BAL outflow, assuming that the BAL region is thick enough for a full development of an ionization front. The total column density of the BAL outflow is constrained in the range N H ∼ 1021–1021.4 cm−2. We also found that the bulk of both Mg ii and UV Fe ii, as well as of Hα broad emission lines (BELs), are blueshifted with a velocity of ∼2200 km s−1 with respect to the quasar systemic redshift. We constrain the blueshifted BEL region to have a covering factor C f  ≈ 16%, density n H ∼ 1010.6–1011.3 cm−3, column density N H ≳ 1023 cm−2, and ionization parameter U E  ∼ 10−2.1–10−1.5. The outflow gas is located at ∼0.1 pc away from the central ionization source, at a scale comparable to the broad-line region. A toy kinetic model has been proposed to reproduce the profile of Mg ii BEL well if a partial obscured axisymmetric geometry of the outflow with a radial velocity as observed from the BALs is assumed.