DOES HOT GAS PERVADE THE LOCAL UNIVERSE

Where, and in what form, are most of the Baryons in the local universe? At highredshift we seem to know the answer, but a substantial fraction of the baryonsseem to be missing at low redshift! It is very likely that this material residesin the haloes of galaxies and galaxy groups, at densities and temperatures thatmake it hard to detect by conventional means. This material should be detectablethrough the OVII and OVIII absorption of a background source. However, we arguethat observation of random sightlines is not effective, and that we mustdeliberately target lines of sight that pass through the centers of galaxygroups. Although very rare, we have identified two particularly favourablesightlines that will allow us to detect this important baryon reservoir. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]