The FIRST-2MASS Red Quasar Survey II: An anomalously high fraction of LoBALs in searches for dust-reddened quasars

TL;DR

This study identifies a high fraction of dust-reddened Type-1 quasars, especially LoBALs, suggesting they are in an early evolutionary stage with significant feedback effects on their host galaxies.

Contribution

It presents a novel survey combining radio, infrared, and optical data to find dust-reddened quasars that traditional methods miss, revealing a high prevalence of LoBALs.

Findings

Over 50% of identified quasars are dust-reddened Type 1.

High fraction of LoBAL quasars among reddened quasars.

Reddenings suggest obscuration in host galaxies rather than dust tori.

Abstract

We present results on a survey to find extremely dust-reddened Type-1 Quasars. Combining the FIRST radio survey, the 2MASS Infrared Survey and the Sloan Digital Sky Survey, we have selected a candidate list of 122 potential red quasars. With more than 80% spectroscopically identified objects, well over 50% are classified as dust-reddened Type 1 quasars, whose reddenings (E(B-V)) range from approximately 0.1 to 1.5 magnitudes. They lie well off the color selection windows usually used to detect quasars and many fall within the stellar locus, which would have made it impossible to find these objects with traditional color selection techniques. The reddenings found are much more consistent with obscuration happening in the host galaxy rather than stemming from the dust torus. We find an unusually high fraction of Broad Absorption Line (BAL) quasars at high redshift, all but one of them belonging to the Low Ionization BAL (LoBAL) class and many also showing absorption the metastable FeII line (FeLoBAL). The discovery of further examples of dust-reddened LoBAL quasars provides more support for the hypothesis that BAL quasars (at least LoBAL quasars) represent an early stage in the lifetime of the quasar. The fact that we see such a high fraction of BALs could indicate that the quasar is in a young phase in which quasar feedback from the BAL winds is suppressing star formation in the host galaxy.