The richest superclusters in SDSS/redMaPPer

Superclusters, as the largest cosmic structures, are important to study theevolution of galaxy clusters and groups, cosmic baryons (e.g., the warm hotintergalactic medium) and galaxy evolution. There have been few studies ofsuperclusters in Xrays, while the Xray data remain as the key to study thebulk of baryons in superclusters. We select the two richest superclusters fromthe SDSS/redMaPPer cluster catalog and propose XMM observations to map both ofthem. They are extreme mass concentrations with the total mass at least severaltimes higher than wellknown superclusters like A901/2. The XMM data will beused to map the mass distribution (along with our weaklensing work), studymerger dynamics and examine the cosmic filaments, and provide us important insights on superclusters. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]