The early stage of massive galaxy evolution often involves outflows driven by a starburst or a central quasar plus cold mode accretion (infall), which adds to the mass build-up in the galaxies. To study the nature of these infall and outflows in the quasar environments, we have examined the correlation of narrow absorption lines (NALs) at positive and negative velocity shifts to other quasar properties, such as their broad absorption-line (BAL) outflows and radio-loudness, using spectral data from SDSS-BOSS DR12. Our results show that the incidence of associated absorption lines (AALs) and outflow AALs is strongly correlated with BALs, which indicates most AALs form in quasar-driven outflows. Multiple AALs are also strongly correlated with BALs, demonstrating quasar outflows tend to be highly structured and can create multiple gas components with different velocity shifts along our line of sight. Infall AALs appear less often in quasars with BALs than quasars without BALs. This suggests that BAL outflows act on large scale in host galaxies and inhibit the infall of gas from the IGM, supporting theoretical models in which quasar outflow plays an important role in the feedback to host galaxies. Despite having larger distances, infall AALs are more highly ionized than outflow AALs, which can be attributed to the lower densities in the infall absorbers.

Associated absorption lines (AALs) in quasar spectra are valuable probes of the gas kinematics and physical conditions in quasar environments. The host galaxies are by definition in an active evolution stage that might involve large-scale blowouts and/or cold-mode accretion (infall) from the intergalactic medium (IGM). We discuss rest-frame UV spectra of four redshift 2-3 quasars selected to have low-ionisation AALs of Si ii or C ii that place unique density and distance constraints on the absorbers. Our analysis of the AALs yields the following results. One of the quasars, Q0119−046, has a rich complex of 11 AAL systems that appear to be infalling at measured speeds from ∼0 to ∼1150 km s −1 at distance ∼5.7 kpc from the quasar. The range of ions detected, up to Ne viii, indicates a wide range of densities from ∼4 to ∼2500 cm −3 . Partial covering the quasar emission source requires cloud sizes <1 pc and possibly <0.01 pc. The short dissipation times of these small clouds suggests that they are created in situ at their observed location, perhaps as dense condensations in cold-mode accreting gas from IGM. The AALs in the other three quasars have outflow speeds from ∼1900 to ∼3000 km s −1 . Some of them also appear to have a range of densities based on the range of ions detected, including Mg i λ2853 in Q0105+061. However, the absence of excited-state AALs yields only upper limits on their gas densities ( 150 cm −3 ) and large minimum distances ( 40 kpc) from the quasars. These AALs might represent highly extended quasar-driven outflows, although their actual physical relationships to the quasars cannot be established.

Rich complexes of associated absorption lines (AALs) in quasar spectra provide unique information about gaseous infall, outflows, and feedback processes in quasar environments. We study five quasars at redshifts 3.1 to 4.4 with AAL complexes containing from 7 to 18 C iv λ1548, 1551 systems in highresolution spectra. These complexes span velocity ranges 3600 km s −1 within 8200 km s −1 of the quasar redshifts. All are highly ionised with no measurable low-ionisation ions like Si ii or C ii, and all appear to form in the quasar/host galaxy environments based on evidence for line locking, partial covering of the background light source, strong N v absorption, and/or roughly solar metallicities, and on the implausibility of such complexes forming in unrelated intervening galaxies. Most of the lines in all five complexes identify high-speed quasar-driven outflows at velocity shifts v −1000 km s −1 . Four of the complexes also have lines at smaller blueshifted velocities that might form in ambient interstellar clouds, low-speed outflows or at feedback interfaces in the host galaxies where high-speed winds impact and shred interstellar clouds. The partial covering we measure in some of the high-speed outflow lines require small absorbing clouds with characteristic sizes 1 pc or 0.01 pc. The short survival times of these clouds require locations very close to the quasars, or cloud creation in situ at larger distances perhaps via feedback/cloud-shredding processes. The AAL complex in one quasar, J1008+3623, includes unusually narrow C iv systems at redshifted velocities 350 v 640 km s −1 that are excellent candidates for gaseous infall towards the quasar, e.g., "cold-mode" accretion or a gravitationally-bound galactic fountain.