Confirmation Of Thick Whim At Z-0.1 In Sculptor Supercluster

This grant is associated to an XMM observation of the quasar QSO Q0056-363(PI: Dr. Roberto Maiolino), which is one of the brightest quasars in the X-ray sky, and it lies in the general direction of the Sculptor Supercluster, and behind it. We requested the observation to check a previous hint of existence of an absorption features by highly ionized gas at the redshift of the Supercluster, which we supposed to be the imprint of a Warm-Hot Intergalactic Medium filament connecting the already virialized structures in the Supercluster. The observation suffered a high background, and so the net exposure was considerably reduced compared to the requested exposure. Additionally the quasar turned out to be in a quite low level of activity. These two unfortunate facts made it impossible to confirm or rule-out at high resolution (i.e. with the RGS) the existence of the previously hinted OW1 K-alpha resonant line at the redshift of the Sculptor Supercluster, the new RGS data being sensitive only to equivalent width of unresolved absorption lines of about 30-50 mA at 1-sigma. The data, however, shows a very strong absorption line in a position different from the OVII/OVIII K-alpha at the redshift of the Supercluster. If this line is interpreted as OVII/OVIII K-alpha absorption, the redshift of this WHIM filament would lie in a region of the Universe where no visible virialized concentrations are present. This would confirm the relatively high probability of detecting WHIM filaments in apparent 'void' regions of the Universe (as previously suggested by our first detection of WHIM filaments at z greater than 0 along the line of sight to the blazar Mkn 421). A paper on the non-detection of any WHIM filament at the redshift of the Sculptor Supercluster, as well as on the detection of this putative WHIM filament in a 'void', will be shortly submitted to the ApJ.