AChandraSurvey of Broad Absorption Line Quasars

We have carried out a survey with the Chandra X-ray Observatory of a sampleof 10 optically bright broad absorption line (BAL) QSOs. Eight out of tensources are detected. The 6 brightest X-ray sources have only high ionizationBALs (hiBALs), while the 4 faintest all show low ionization BALs (loBALs). Weperform a combined spectral fit for hiBAL QSOs to determine the mean spectralparameters of this sample. We derive an underlying best-fit power-law slopeGamma=1.8+/-0.35, consistent with the mean slope for radio-quiet quasars fromASCA, but BALQSOs require a (restframe) absorbing column of 6.5e22, with apartial covering fraction of 80%. Removing the absorption component from ourbest-fit spectral model yields a range of alphaOX from 1.55 to 2.28. All 6hiBAL QSOs have de-absorbed X-ray emission consistent with non-BAL QSOs ofsimilar luminosity. The spectral energy distributions of the hiBAL QSOs - boththe underlying power-law slope and alphaOX provide the first conclusiveevidence that BALQSOs have appeared to be X-ray weak because of intrinsicabsorption, and that their underlying emission is consistent with non-BAL QSOs.By contrast, removal of the best-fit absorption column detected in the hiBALQSOs still leaves the 4 loBAL QSOs as unusually X-ray faint for their opticalluminosities.