X-rays from the highly polarized broad absorption line QSO CSO 755

We present results from a BeppoSAX observation of the broad absorption line (BAL) QSO CSO 755, which was observed as part of our program to investigate the X-ray properties of highly polarized BAL QSOs, CSO 755 is clearly detected by the BeppoSAX Medium-Energy Concentrator Spectrometers, making it the highest redshift (z = 2.88) and most optically luminous (M-V = -27.4) BAL QSO seen in X-rays. It is detected in several energy bands including the rest-frame 21-39 keV band, but we are able to place only loose constraints upon its X-ray spectral shape. Our X-ray detection is consistent with the hypothesis that the BAL QSOs with high optical continuum polarization tend to be the X-ray brighter members of the class, We examine a scattering interpretation of a polarization/X-ray flux connection, and we discuss the data needed to prove or refute such a connection. We also discuss a probable ROSAT detection of CSO 755, The observed-frame 2-10 keV flux from BeppoSAX (1.3 x 10(-13) ergs cm(-2) s(-1)) is high enough to allow X-Rn) Multimirror Mission spectroscopy, and studies of iron K-line emission should prove of particular interest if a large amount of scattered X-ray flux is present.