MAGNETIC-FIELDS IN THE HYDRA-A CLUSTER

Sensitive, high-resolution VLA polarimetric observations are presented for the radio galaxy Hydra A, an outstanding example of a high-lumino sity radio source embedded within a cooling flow cluster. We find extr emely high Faraday rotation measures (RMs), throughout the central reg ions of this source, with a strong asymmetry between the north and sou th lobes. Simple models for the high RMs are discussed and compared wi th the observations. To explain the north-south asymmetry in RM requir es a magnetic field of strength approximately 6 muG organized over a s cale of approximately 100 kpc. On smaller scales we find a tangled mag netic field with a strength of approximately 30 muG.