On the Nature of the Sculptor Wall X-ray Absorber

Although most of the WarmHot Intergalactic Medium (WHIM) has yet to be found,an extremely promising candidate for the typical WHIM gas is our detection of anOVII Kalpha absorption line located in the Sculptor Wall superstructure ofgalaxies (z virgul0.03). We propose a deep 500ks RGS observation of the Sculptor Wallabsorber that will detect the OVII Kbeta line at the 4sigma level and the OVIIKalpha line at >5sigma level. Not only will the existence of the Kbeta lineprovide crucial objective evidence for the WHIM nature of the absorber, but theconstraints obtained on the absorber properties will be sufficiently precise todistinguish it from the type of gas found in a galaxy like the Milky Way, andfrom the high density tail of the WHIM detected in Xray emission. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]