A View of PKS 2155-304 with XMM-Newton Reflection Grating Spectrometers

We present the high-resolution X-ray spectrum of the BL Lac object PKS 2155-304 taken with the RGS units on board XMM-Newton in 2000 November. We detect an O VII Kα resonant absorption line from warm/hot local gas at 21.59 Å (~4.5 σ detection). The line profile is possibly double peaked. We do not confirm the strong 20.02 Å absorption line seen with Chandra and interpreted as z~0.05 O VIII Kα. We set a 3 σ upper limit of 14 mÅ on the equivalent width. We also detect the ~23.5 Å interstellar O I 1s-->2p line and derive a factor of <=1.5 subsolar O/H ratio in the interstellar medium along the PKS 2155-304 line of sight.