The Virial Radius of 2 keV Clusters

The breaking of selfsimilarity in virialised systems occurs in the mass regime least amenable to global study of its hot gas, due to the low surface brightness of Xray halos in small systems. Inability to determine the virial radius with certainty undermines attempts to study the scaling properties of systems across a wide range of masses. XMM offers the first opportunity to resolve this issue, with a direct determination of the virial radius in 2keV clusters, which are cool enough to be strongly affected by nongravitational processes, but bright enough to provide good statistics. These observations will permit us to map the gas properties out to large radii and hence establish whether trends reported in the M:T relation and the gas fraction are real or spurious. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]