The formation mechanism of bright isolated elliptical galaxies

It is as yet unclear what processes govern the formation of ellipticals in thelowest density environments. While low luminosity ellipticals may form throughthe merger of isolated pairs of spiral galaxies, the only models advanced forforming bright ellipticals in these environments are monolithic collapse or thecomplete merger of all major galaxies in a group. A small number of suchfossil.. groups have been identified. We propose to determine whether fossilgroups make up the majority of the population of luminous isolated ellipticalsby observing an optically selected sample of 3 such galaxies, to ascertainwhether their Xray properties are those of groups or individual galaxies. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]