Clusters on the Edge: The Interface Between Galaxy Cluster Outskirts and Large-Scale Intercluster Filaments
Alvarez, Gabriella Elan Clapper
There is a large-scale structure to the Universe, known as the cosmic web. Galaxy Clusters, consisting of hundreds to thousands of galaxies, form along and at the nodes of the cosmic filaments that make up this web. This thesis seeks to explore how the large-scale structure of the Universe has formed and evolved through time by investigating X-ray observations of galaxy clusters that are in the early stages of the merging process. Specifically Abell 3391/Abell 3395 (A3391/A3395), a double cluster system with an intercluster filament connecting the two clusters, is studied using Chandra, and XMM-Newton observations. Abell 98 (A98), a triple cluster system aligned along a purported intercluster filament is studied using Suzaku, Chandra, and XMM-Newton observations. It is found that the A3391 and A3395 are most likely having their intracluster medium (ICM) gas tidally pulled into the intercluster filamentary region as part of an early stage merger. The northernmost cluster of A98, A98N, is found to be consistent with self-similar expectations. There also appears to be a bridge of gas connecting A98N and A98S, the central cluster in the A98 system. Both systems were found to have tentative evidence of the warm-hot intergalactic medium (WHIM) present, which could solve the supposed “missing baryon problem”, in which observations reveal that the amount of baryons in the local Universe does not match expectations.