Presentation #428.09 in the session Galaxy Clusters.
Shock fronts provide an essential observational tool in probing the physics of transport process in the ICM, including electron-ion equilibrium and thermal conduction, magnetic fields, and turbulence. X-ray observations of merger shocks with a sharp density edge and an unambiguous jump in temperature are relatively rare. In most cases, the shock has been detected in the later stage of the merging process. Here we report the first unambiguous detection of an axial merger shock in an early-stage merger in Abell 98. Our discovery of axial merger shock front unveils a critical epoch in the formation of a massive galaxy cluster when two sub-clusters are caught in the early phase of the merging process. We also report X-ray observations of a filament of gas at 107 K along the merger axis of Abell 98. Our measured properties of the gas in the filament are consistent with previous observations and numerical simulations of the hottest, densest parts of the warm-hot intergalactic medium (WHIM).