X-RAY ABSORPTION BY WHIM IN THE SCULPTOR WALL

Abstract

We present XMM RGS and Chandra LETG observations of the blazar, H 2356-309,\nlocated behind the Sculptor Wall, a large-scale galaxy structure expected to\nharbor high-density Warm-Hot Intergalactic Medium (WHIM). Our simultaneous\nanalysis of the RGS and LETG spectra yields a 3-sigma detection of the crucial\nredshifted O vii K-alpha line with a column density (>~ 10^{16} cm^{-2})\nconsistent with similar large-scale structures produced in cosmological\nsimulations. This represents the first detection of non-local WHIM from X-ray\nabsorption studies where XMM and Chandra data are analyzed simultaneously and\nthe absorber redshift is already known, thus providing robust evidence for the\nexpected repository of the "missing baryons".\n