VLT/X-Shooter Survey of BAL Quasars: Large Distance Scale and AGN Feedback

Abstract

Abstract We conducted a survey of quasar outflows using the Very Large Telescope/X-Shooter spectrograph. When choosing the 14 broad absorption line (BAL) and mini-BALs comprising this sample, the data did not cover the S iv and S iv* troughs, whose ratio can be used to determine the distance of the outflows from the central source (R). Therefore, this “Blind Survey” is unbiased toward a particular distance scale. Out of the eight outflows where R can be measured, six have R > 100 pc (spanning the range 100–4500 pc), one has R > 10 pc, and only one (at R < 40 pc) is compatible with a much smaller R scale. At least two of the outflows have a kinetic luminosity greater than 0.5% of their Eddington luminosity, implying that they are able to provide significant active galactic nucleus (AGN) feedback. The outflows span a range of 0 to −10,000 km s−1 in velocity, total column density between 1020.1 and 1022.6 cm−2, ionization parameter ( ) in the range 0.01–1, and electron number density between 103.2 and 105.4 cm−3, with one upper and one lower limit. The results of this survey can be extrapolated to the majority of BAL outflows, implying that most of these outflows are situated far away from the AGN accretion disk, and that a significant portion of them can contribute to AGN feedback processes.