ChandraDetection of X‐Ray Absorption Associated with a Damped Lyα System

We have observed three quasars, PKS 1127-145, Q 1331+171 and Q0054+144, withthe ACIS-S aboard the Chandra X-ray Observatory, in order to measure soft X-rayabsorption associated with intervening 21-cm and damped Ly$\alpha$ absorbers.For PKS 1127-145, we detect absorption which, if associated with an interveningz_{abs}=0.312 absorber, implies a metallicity of 23% solar. If the absorptionis not at z_{abs}=0.312, then the metallicity is still constrained to be lessthan 23% solar. The advantage of the X-ray measurement is that the derivedmetallicity is insensitive to ionization, inclusion of an atom in a molecule,or depletion onto grains. The X-ray absorption is mostly due to oxygen, and isconsistent with the oxygen abundance of 30% solar derived from optical nebularemission lines in a foreground galaxy at the redshift of the absorber. For Q1331+171 and Q 0054+144, only upper limits were obtained, although theexposure times were intentionally short, since for these two objects we wereinterested primarily in measuring flux levels to plan for future observations.The imaging results are presented in a companion paper.Comment: 23 pages, 6 figures, accepted for publication in the Astrophysical Journa