Absorption-line Environments of High-redshift BOSS Quasars

TL;DR

This study investigates the environments of high-redshift quasars by analyzing absorption lines, revealing that quasar outflows are structured and can inhibit gas infall, supporting feedback models in galaxy evolution.

Contribution

It provides new insights into the correlation between absorption lines and quasar outflows, demonstrating the structured nature of outflows and their impact on gas infall in galaxy evolution.

Findings

Associated absorption lines are strongly linked to quasar outflows.

Multiple absorption lines indicate highly structured outflows.

Infall absorption lines are less common in quasars with outflows, suggesting feedback effects.

Abstract

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.