X-ray observation of a massive strong-lensing galaxy group HSC J1441-0053

The dark matter selfinteraction crosssection depends on velocity and theirmodel claims to explain observations from dwarfs to massive clusters. We need totest these models at galaxy group scales, where no usable data exist. Analysisfrom even a single system will be valuable. We propose a 40 ksec observation ofa massive galaxy group HSC J14410053 to put the first constraints in this massrange. This is no ordinary (lensing) galaxygroup it has lensed images ofdifferent sources at varying angular radii which allows us to get more accurateconstraints on the inner density profile than any other (non) lensing galaxygroups at similar masses and redshift. The accurate centroid determination andindependent mass estimation with XMM are vital to derive accurate mass model. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]