On the Nature of the Sculptor Wall X-ray Absorber

This is a continuation of an approved AO11 program. Although most of theWarmHot Intergalactic Medium (WHIM) has yet to be found, an extremely promisingcandidate for the typical WHIM gas is our detection of an OVII Kalphaabsorption line located in the Sculptor Wall superstructure of galaxies(zvirgul0.03). We propose a deep 390ks RGS observation of the Sculptor Wall absorberthat, combining with the planned AO11 program, will detect the OVII Kbeta lineat the 4sigma level and the OVII Kalpha line at >5sigma level. The existenceof the Kbeta line provide crucial objective evidence for its WHIM nature, anddistinguish the absorber from the type of gas found in a galaxy like the MilkyWay, and from the high density tail of the WHIM detected in emission. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]