Soft X-ray Transmission Spectroscopy of Warm/Hot Intergalactic Medium   with XEUS
  We discuss the detectability of Warm/Hot Intergalactic medium (WHIM) via the 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 GRB afterglows. We create mock absorption spectra for bright QSOs (more than 20 QSOs over the all sky) using a light-cone output of a cosmological hydrodynamic simulation. We assume that WHIM is under collisional and photo-ionization equilibrium. If WHIM has a constant metallicity of $Z=0.1Z_\odot$, approximately 2 O{\sc vii} absorption line system with $>3\sigma$ will be detected on average along a random line-of-sight toward bright QSOs up to $z=0.3$ for 30 ksec exposure. 
Hajime Kawahara, Kohji Yoshikawa, Shin Sasaki, Yasushi Suto, Nobuyuki   Kawai, Kazuhisa Mitsuda, Takaya Ohashi, and Noriko Y...