2021MNRAS.506.2725X

Quasar Q0059-2735, one of the first known iron low-ionization broad-absorption-line quasars (FeLoBAL), has a plethora of outflow absorption features at different velocities. Given multiple outflow systems, their troughs from high-ionization transitions form very wide BAL features, e.g. C IV troughs extend from ∼-1000 to -25 000 km s^–1. The troughs from low-ionization transitions show more than 1000 narrow absorption lines (NALs) with velocities from -1000 to -3000 km s^–1. These include troughs from iron-peak elements, e.g. Fe II, Fe III, Cr II, Mn II, Ni II, and Co II, which are rarely detected in quasar outflows. Most of these troughs are non-black saturated. We constrain the physical conditions of the NALs by fitting the observed Fe II and Fe III absorption troughs. We find that the Fe II absorption arises from a region with an electron temperature (T_e) of ∼8000 K and an electron number density (n_e) of ∼10⁸ cm^–3. The same model also fits well the troughs from other iron-peak elements. In contrast to the Fe II lines, Fe III lines are formed in a hotter region, i.e. T_e ∼20 000 K. To fit the Fe II and Fe III lines simultaneously in a single photoionized cloud, they require a supersolar iron abundance and/or other heating mechanisms for the Fe III region. The distance (R) of the outflows to the central quasar is determined to be ∼40 pc. The high-resolution data afforded by the Very Large Telescope (VLT)/UVES observations from 2006 and 2018, along with the narrow lines, allow us to constrain the smallest outflow deceleration in any known quasars.