The rest-frame ultraviolet properties of radio-loud broad absorption line quasars

TL;DR

This study compares the ultraviolet properties of radio-loud BAL quasars with non-BAL quasars, finding similar outflow characteristics across different orientations and noting some differences in continuum redness and Fe II emission.

Contribution

It provides the first detailed comparison of UV properties between radio-loud BAL and non-BAL quasars, highlighting the universality of BAL outflows regardless of orientation.

Findings

Radio-loud BAL quasars have similar UV properties to non-BAL quasars.

BAL quasars tend to have redder continua and stronger Fe II emission.

No correlation between outflow properties and radio spectral index.

Abstract

We recently presented radio observations of a large sample of radio-loud broad absorption line (BAL) quasars from the SDSS and FIRST surveys, as well as a well matched sample of unabsorbed quasars, primarily to measure their radio spectral indices and estimate ensemble orientations. Here, we analyze the SDSS spectra of these samples and compare the rest-frame ultraviolet properties of radio-loud BAL and non-BAL quasars. Ultraviolet properties include the continuum shape, emission-line measurements of C IV, Al III, C III], Fe II, and Mg II, and BAL properties including the balnicity index (BI), absorption index (AI), and minimum and maximum outflow velocities. We find that radio-loud BAL quasars have similar ultraviolet properties compared to radio-loud non-BAL sources, though they do appear to have redder continua and stronger Fe II emission, which is consistent with what is found for radio-quiet BAL sources. No correlations exist between outflow properties and orientation (radio spectral index), suggesting that BAL winds along any line of sight are driven by the same mechanisms. There are also few correlations between spectral index and other properties. We conclude that BAL outflows occur along all lines of sight with similar strengths and velocities.