ABELL-548 - AN X-RAY AND OPTICAL ANALYSIS OF SUBSTRUCTURE

X-ray observations of Abell 548 reveal that the hot gas in this cluste r is at least as complex as the galaxy distribution. Our ROSAT Positio n Sensitive Proportional Counter image is used in conjunction with opt ical data from the Minnesota plate-scanning project and redshift data in the literature to investigate the degree of substructure in the int racluster medium and the galaxy distribution. A548 has several X-ray c omponents: hot gas associated with clumps of galaxies, individual sour ces, and a newly discovered diffuse component. This diffuse component may be primordial gas falling into the cluster for the first time. The optical data suggest that this cluster consists of four major compone nts, not three (as indicated when velocity data are ignored). Simple m odels of the orbital dynamics suggest that the cluster may not yet hav e reached its turnaround radius.