SHOCK FRONT IN A521 AND NEW METHOD OF MEASURING INTRACLUSTER MAGNETIC FIELD

Shock fronts provide a unique tool to study the cluster plasma. So far only twounambiguous examples have been discovered, those in 1E0657 and A520. We proposeto confirm and quantify another candidate, an Xray brightness edge detected ina short Chandra observation of A521 at the location of a prominent radio relic.Owing to its geometry and the excellent multifrequency radio data on the relic,this shock front will enable a novel measurement of the intracluster magneticfield, based on the width of the radio relic and the gas velocities determinedfrom the Xray data. The proposed observation will unambiguously confirm theexistence of the brightness edge and the fact that this is a shock front, anddetermine its Mach number. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]