Finishing a representative sample of local galaxy groups

Galaxy groups are ideal systems to study baryon physics, which is important forboth using clusters for precision cosmology and understanding galaxy formationand evolution. Over the last decade, our understanding on the ICM properties ofgalaxy groups has been greatly improved. However, there is no a representativegroup sample with Chandra or XMM that allows full coverage to r_500. We definedsuch a sample of 13 galaxy groups that are Xray luminosity selected from the400 deg^2 survey (REGOS4). The lowL_X bin was approved in the last XMM cycle.Complete Chandra coverage (mostly short exposures) and other supporting datahave also been obtained. We now propose to observe the highL_X bin with XMM tofinish REGOS4 and ensure a continuous L_X coverage from REXCESS to REGOS4. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]