The X-Ray Absorber in Broad Absorption Line Quasars

Abstract

Recent observations of Broad Absorption Line (BAL) quasars demonstrated that the soft X-ray emission of these objects is extremely weak and convincing evidence for very strong absorption by a high column density (~ 10^23.5 cm^-2) was obtained for PG 1411+442, even though it is one of the few BAL QSOs strongly detected in soft X-rays. This paper examines the ionization status and geometry of the X-ray absorber by combining the properties of the UV lines with the X-ray continuum absorption. We show that the gas has to have large column densities in ions of major UV absorption lines, such as CIV, NV, OVI and Ne VIII, in order to have sufficient opacity around 0.2 to 0.35 keV. The UV absorption lines have to be saturated if the X-ray absorber intersects the line of sight to the UV continuum emission region. A uniformly covering UV and X-ray absorption model can be constructed for PG 1411+442 but in some other soft X-ray detected BAL QSOs, such as PG 1001+054, the observed line optical depth is much lower than expected from the X-ray absorbing material. We propose a scheme in which a substantial fraction of the line of sight to the continuum source may be covered by either an optically thick flow or clouds in a narrow velocity range, but in which the total covering factor of either the whole flow or all clouds is close to unity.

arXiv comment11 pages, 6 figures, replacement of figure 1

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Cited by in corpus (9)

• A Composite Extreme Ultraviolet QSO Spectrum from the Far Ultraviolet Spectroscopic Explorer
• Evidence for Photoionization Driven Broad Absorption Line Variability
• The Correlation between X-ray and UV Properties of BAL QSOs
• Carbon and Nitrogen Abundance Ratio In the Broad Line Region of Tidal Disruption Events
• Jet break time -- flux density relationship and constraints on physical parameters of GRB afterglows
• Detection of an Iron Emission Feature from the Lensed BAL QSO H1413+117 at z=2.56
• Polarization of Quasars: Resonant Line Scattering in the Broad Absorption Line Region
• Active Galaxies in the UV
• Fast Outflowing Warm Absorbers in Narrow-Line Seyfert 1 Galaxy PG 1001+054 Revealed by HST/COS Spectra