Extreme High-velocity Outflows from High-redshift BOSS Quasars

TL;DR

This study investigates extremely high-velocity narrow absorption lines in high-redshift quasars, revealing they are often intrinsic to quasars and related to outflows, radio jets, and radiative forces, challenging the notion they are unrelated intervening gas.

Contribution

It demonstrates that a significant portion of high-velocity NALs originate from quasar outflows and are physically connected to intrinsic quasar activity, supported by correlations with BALs and radio properties.

Findings

High-velocity NALs are correlated with AALs, BALs, and radio loudness.

Line-locked NALs are highly ionized and linked to outflows.

Evidence suggests many high-velocity NALs are intrinsic to quasars.

Abstract

It is common to assume that all narrow absorption lines (NALs) at extreme high-velocity shifts form in cosmologically intervening gas or galaxies unrelated to quasars. However, previous detailed studies of individual quasars have shown that some NALs at these large velocity shifts do form in high-speed quasar ejecta. We search for extreme high-velocity NAL outflows (with speeds $\sim$0.1-0.2c) based on relationships with associated absorption lines (AALs) and broad absorption-line (BAL) outflows. We find that high-velocity NALs are strongly correlated with AALs, BALs, and radio loudness, indicating that a significant fraction of high-velocity systems are either ejected from the quasars or form in material swept up by the radio jets (and are not unrelated intervening gas). We also consider line-locked C IV doublets as another indicator of high-velocity NALs formed in outflows. The fact that line-locked NALs are highly ionized and correlated with BAL outflows and radio-loud quasars implies that physical line locking due to radiative forces is both common and real, which provides indirect evidence that a significant fraction of high-velocity NALs are intrinsic to quasars.