BAL Outflow Contribution to AGN Feedback: Frequency of S iv Outflows in the SDSS

TL;DR

This study investigates S IV outflows in SDSS quasar spectra to determine their frequency, physical properties, and contribution to AGN feedback, providing insights into the distance and energetics of BAL outflows.

Contribution

It is the first to analyze the frequency of S IV outflows in a large SDSS quasar sample and to constrain their covering factors and distances, enhancing understanding of AGN feedback mechanisms.

Findings

14% of bright SDSS quasars show C IV BALs.

1.9% of bright SDSS quasars show S IV BALs.

S IV outflows can be located several kiloparsecs from the AGN.

Abstract

We present a study of Broad Absorption Line (BAL) quasar outflows that show S IV ?1063 and S IV* ?1073 troughs. The fractional abundance of S IV and C IV peak at similar value of the ionization parameter, implying that they arise from the same physical component of the outflow. Detection of the S IV* troughs will allow us to determine the distance to this gas with higher resolution and higher signal-to-noise spectra, therefore providing the distance and energetics of the ubiquitous C IV BAL outflows. In our bright sample of 156 SDSS quasars 14% show C IV and 1.9% S IV troughs, which is consistent with a fainter magnitude sample with twice as many objects. One object in the fainter sample shows evidence of a broad S IV trough without any significant trough present from the excited state line, which implies that this outflow could be at a distance of several kpc. Given the fractions of C IV and S IV, we establish firm limits on the global covering factor on S IV that ranges from 2.8% to 21% (allowing for the k-correction). Comparison of the expected optical depth for these ions with their detected percentage suggests that these species arise from common outflows with a covering factor closer to the latter.