Strong X-Ray Absorption in a Broad Absorption Line Quasar: PHL 5200

Abstract

We present ASCA observations of the 2 = 1.98 prototype broad absorption line quasar (BALQSO): PHL5200. The source was detected in both SIS and GIS. A power-law spectrum (αE = 0.6+0.9-0.6)with large intrinsic absorption (Nh = 1.3+2.3-1.1 X 1023 cm-2) best describes the spectrum. Excess column density over the local Galactic value is required at the 99% confidence level. This detection suggests that, although BALQSOs are X-ray-quiet, it is strong absorption in the BAL region that makes them appear faint to low-energy X-ray experiments. The required intrinsic absorbing column density is 2-3 orders of magnitude larger than earlier estimates of column densities in BALQSOs. This implies that the BAL systems are much more highly ionized than was previously thought. © 1995. The American Astronomical Society. All rights reserved. Printed in U.S.A.