The most powerful quasar outflows as revealed by the Civ {\lambda}1549 resonance line

TL;DR

This study analyzes high-luminosity quasars to reveal that powerful, high-velocity outflows, traced by Civ λ1549 lines, become more frequent with increasing luminosity, impacting host galaxy evolution.

Contribution

It provides new observational evidence linking quasar luminosity with outflow strength and offers insights into the feedback processes in luminous quasars using the 4DE1 framework.

Findings

High-luminosity quasars exhibit more frequent and powerful outflows.

Accurate systemic redshifts enable precise velocity shift measurements.

Outflows likely contribute significantly to galaxy feedback mechanisms.

Abstract

While quasar outflows may be quasi-ubiquitous, there are significant differences on a source-by- source basis. These differences can be organized along the 4D Eigenvector 1 sequence: at least at low z, with only Population A sources radiating at relatively high Eddington ratio and showing prominent high-velocity outflows in Civ {\lambda}1549 line profiles. We discuss in this paper VLT-FORS observations of Civ {\lambda}1549 emission line profiles for a high-luminosity sample of Hamburg- ESO quasars and how they are affected by outflow motion as a function of quasar luminosity. Our high- luminosity sample has the notable advantage that the rest frame has been accurately determined from previous VLT-ISAAC observations of H{\beta} in the J, H, and K bands. This makes measures of inter-line velocity shifts accurate and free of systemic biases. As the redshift increases and the luminosity of the brightest quasars increases, powerful, high-velocity outflows become more frequent. We discuss the outflow contextualisation, fol- lowing the 4DE1 formalism, as a tool for understanding the nature of the so-called weak lined quasars (WLQ) discovered in recent years as a new, poorly understood class of quasars. We estimate the kinetic power associ- ated with Civ {\lambda}1549 outflows and suggest that the host galaxies in the most luminous sources likely experience significant feedback.