An Infrared Excess Identified in Radio-Loud Broad Absorption Line Quasars

Abstract

If broad absorption line (BAL) quasars represent a high covering fraction evolutionary state (even if this is not the sole factor governing the presence of BALs), it is expected that they should show an excess of mid-infrared radiation compared to normal quasars. Some previous studies have suggested that this is not the case. We perform the first analysis of the IR properties of radio-loud BAL quasars, using IR data from WISE and optical (rest-frame ultraviolet) data from SDSS, and compare the BAL quasar sample with a well-matched sample of unabsorbed quasars. We find a statistically significant excess in the mid- to near-infrared luminosities of BAL quasars, particularly at rest-frame wavelengths of 1.5 and 4 microns. Our sample was previously used to show that BALs are observed along many lines of sight towards quasars, but with an overabundance of more edge-on sources, suggesting that orientation factors into the appearance of BALs. The evidence here---of a difference in IR luminosities between BAL quasars and unabsorbed quasars---may be ascribed to evolution. This suggests that a merging of the current BAL paradigms is needed to fully describe the class.

Accepted to ApJ

References in corpus (10)

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Cited by in corpus (11)

• Near-IR spectroscopy of luminous LoBAL quasars at 1<z<2.5
• Broad Absorption Line Variability in Radio-Loud Quasars
• The orientation dependence of quasar spectral energy distributions
• Rest-frame optical properties of luminous, radio-selected, broad absorption line quasars
• Unveiling the Intrinsic X-ray Properties of Broad Absorption Line Quasars with a Relatively Unbiased Sample
• Using the Properties of Broad Absorption Line Quasars to Illuminate Quasar Structure
• A SCUBA-2 survey of FeLoBAL QSOs: Are FeLoBALs in a `transition phase' between ULIRGs and QSOs?
• Radio-Loud and Radio-Quiet BAL Quasars: A Detailed Ultraviolet Comparison
• Investigating the radio-loud phase of broad absorption line quasars
• The X-ray Spectrum and Spectral Energy Distribution of FIRST J155633.8+351758: a LoBAL Quasar with a Probable Polar Outflow
• A multi-wavelength continuum characterization of high-redshift broad absorption line quasars