High-resolution Keck spectra of the associated absorption lines in 3C 191

Associated absorption lines (AALs) are valuable probes of the gaseous environments near quasars. Here we discuss high-resolution (6.7 km s(-1)) spectra of the AALs in the radio-loud quasar 3C 191 (redshift z = 1.956). The measured AALs have ionizations ranging from Mg I to N V and multicomponent profiles that are blueshifted by similar to 400 to similar to 1400 km s(-1) relative to the quasar's broad emission lines. These data yield the following new results : (1) The strengths of excited-state Si II* AALs indicate a density of similar to 300 cm(-3) in the Si+ gas. (2) If the gas is photoionized, this density implies a distance of similar to 28 kpc from the quasar. Several arguments suggest that all of the lines form at approximately this distance. (3) The characteristic flow time from the quasar is thus similar to3 x 10(7) yr. (4) Strong Mg I AALs identify neutral gas with very low ionization parameter and high density. We estimate n(H) greater than or similar to 5 x 10(4) cm(-3) in this region, compared to similar to 15 cm(-3) where the N V lines form. (5) The total column density is N-H less than or similar to 4 x 10(18) cm(-2) in the neutral gas and N-H similar to 2 x 10(20) cm(-2) in the moderately ionized regions. These column densities are consistent with 3C 191's strong soft X-ray flux and the implied absence of soft X-ray absorption. (6) The total mass in the AAL outflow is M similar to 2 x 10(9) M., assuming a global covering factor (as viewed from the quasar) of similar to 10%. (7) The absorbing gas only partially covers the background light source(s) along our line(s) of sight, requiring absorption in small clouds or filaments less than 0.01 pc across. The ratio N-H/n(H) implies that the clouds have radial (line-of-sight) thicknesses less than or similar to 0.2 pc. These properties might characterize a subclass of AALs that are physically related to quasars but form at large distances. We propose a model for the absorber in which pockets of dense neutral gas are surrounded by larger clouds of generally lower density and higher ionization. This outflowing material might be leftover from a blowout associated with a nuclear starburst, the onset of quasar activity, or a past broad absorption line (BAL) wind phase.