X-rays from the Highly Polarized Broad Absorption Line QSO CSO 755

Abstract

We present results from a BeppoSAX observation of the BAL QSO CSO 755, 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 MECS, 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 only able to place 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} erg cm^{-2} s^{-1}) is high enough to allow XMM spectroscopy, and studies of iron K line emission should prove of particular interest if a large amount of scattered X-ray flux is present.

13 pages, ApJL accepted, also available from http://www.astro.psu.edu/users/niel/papers/papers.html