A VLBI survey of compact Broad Absorption Lines (BAL) quasars with BALnicity Index BI=0

Abstract

We present high-resolution observations, using both the European VLBI Network (EVN) at 1.7-GHz, and the Very Long Baseline Array (VLBA) at 5 and 8.4-GHz to image radio structures of 14 compact sources classified as broad absorption line (BAL) quasars based on the absorption index (AI). All source but one were resolved, with the majority showing core-jet morphology typical for radio-loud quasars. We discuss in details the most interesting cases. The high radio luminosities and small linear sizes of the observed objects indicate they are strong young AGNs. Nevertheless, the distribution of the radio-loudness parameter, log(Ri), of a larger sample of AI quasars shows that the objects observed by us constitute the most luminous, small subgroup of AI population. Additionally we report that for the radio-loudness parameter, the distribution of AI quasars and those selected by using the traditional balnicity index (BI), BI quasars differ significantly. Strong absorption is connected with the lower log(Ri), and thus probably with larger viewing angles. Since, the AI quasars have on average larger log(Ri), the orientation can cause that we see them less absorbed. However, we suggest that the orientation is not the only parameter that affects the detected absorption. The fact that the strong absorption is associated with the weak radio emission is equally important and worth exploring.

14 pages, 5 figures, published in MNRAS

References in corpus (18)

• The Sloan Digital Sky Survey Quasar Catalog IV. Fifth Data Release
• CRATES: An All-Sky Survey of Flat-Spectrum Radio Sources
• A Catalog of Broad Absorption Line Quasars in Sloan Digital Sky Survey Data Release 5
• DiFX: A software correlator for very long baseline interferometry using multi-processor computing environments
• Signals from the Noise: Image Stacking for Quasars in the FIRST Survey
• The VLBA Imaging and Polarimetry Survey at 5 GHz
• The Intrinsic Fraction of Broad Absorption Line Quasars
• Outflows and the Physical Properties of Quasars
• Luminous K-band Selected Quasars from UKIDSS
• The Physical Nature of Polar Broad Absorption Line Quasars
• Dependence of the BALQSO fraction on Radio Luminosity
• Radio spectra and polarisation properties of radio-loud Broad Absorption Line Quasars
• Correlations of Quasar Optical Spectra with Radio Morphology
• The Compact Structure of Radio-Loud Broad Absorption Line Quasars
• FIRST-based survey of Compact Steep Spectrum sources, V. Milliarcsecond-scale morphology of CSS objects
• Broad Absorption Line Variability in Radio-Loud Quasars
• A Chandra Survey of the X-ray Properties of Broad Absorption Line Radio-Loud Quasars
• Radio-Loud and Radio-Quiet BAL Quasars: A Detailed Ultraviolet Comparison

Cited by in corpus (1)

• A VLBI survey of compact broad absorption line quasars with balnicity index BI>0