X-ray halos as a possible constraint on an intergalactic dust component

We propose to use the dust scattered X-ray halo of the quasar 3C273 to check the existence of an intergalactic dust component placed along the line of sight in an intergalactic cloud. Based on numerical models we point out that the intensity profile of the X-ray halo could enable to set constraints on the the galactic extinction along the line of sight, the contribution of extragalactic dust to the observed halo as well as its distribution between the X-ray source and the observer.