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We investigate the N  v absorption signal along the line of sight of background quasars, in order to test the robustness of the use of this ion as the criterion to select intrinsic (i.e. physically related to the quasar host galaxy) narrow absorption lines (NALs). We build composite spectra from a sample of ∼ 1000 C  iv absorbers, covering the redshift range 2.55 < z < 4.73, identified in 100 individual sight lines from the XQ-100 Legacy Survey. We detect a statistically significant N  v absorption signal only within 5000 km s−1 of the systemic redshift, |$z_{\rm em}$|⁠. This absorption trough is ∼ 15 σ when only C  iv systems with N (C  iv) > 1014 cm−2 are included in the composite spectrum. This result confirms that N  v offers an excellent statistical tool to identify intrinsic systems. We exploit stacks of 11 different ions to show that the gas in proximity to a quasar exhibits a considerably different ionization state with respect to gas in the transverse direction and intervening gas at large velocity separations from the continuum source. Indeed, we find a dearth of cool gas, as traced by low-ionization species and in particular by Mg  ii, in the proximity of the quasar. We compare our findings with the predictions given by a range of cloudy ionization models and find that they can be naturally explained by ionization effects of the quasar. [ABSTRACT FROM AUTHOR]

Quasar outflows have long been recognized as potential contributors to the co-evolution between supermassive black holes (SMBHs) and their host galaxies. The role of outflows in active galactic nucleus (AGN) feedback processes can be better understood by placing observational constraints on wind locations and kinetic energies. We utilize broad absorption line (BAL) variability to investigate the properties of a sample of 71BAL quasarswith P V broad absorption. The presence of P V BALs indicates that other BALs like C IV are saturated, such that variability in those lines favours clouds crossing the line of sight.We use these constraints with measurements of BALvariability to estimate outflowlocations and energetics. Our data set consists of multiple-epoch spectra from the Sloan Digital Sky Survey and MDM Observatory. We detect significant (4σ) BAL variations from 10 quasars in our sample over rest-frame timescales between ≤0.2-3.8 yr. Our derived distances for the 10 variable outflows are nominally ≲1-10 pc from the SMBH using the transverse-motion scenario, and ≲100-1000 pc from the central source using ionization-change considerations. These distances, in combination with the estimated high outflow column densities (i.e. NH ≳ 1022 cm-2), yield outflow kinetic luminosities between ~0.001 and 1 times the bolometric luminosity of the quasar, indicating that many absorber energies within our sample are viable for AGN feedback. [ABSTRACT FROM AUTHOR]