Soft X-Ray Transmission Spectroscopy of a Warm/Hot Intergalactic Medium with XEUS

We discuss the detectability of a Warm/Hot Intergalactic Medium (WHIM) via absorption lines toward bright point sources with a future X-ray satellite mission, XEUS. While we consider bright QSOs as specific examples, the methodology can be applied to bright gamma-ray burst afterglows. We created mock absorption spectra for bright QSOs (more than 20 QSOs over all sky) using the light-cone output of a cosmological hydrodynamic simulation. We assumed that the WHIM is under collisional and photo-ionization equilibrium. If WHIM has a constant metallicity of Z =0.1Z� , approximately 2 O VII absorption line systems with >3σ will be detected on average along a random line-of-sight toward bright QSOs up to z =0 .3 for a 30ks exposure.