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-luminosity radio source embedded within a cooling flow cluster. We find extremely high Faraday rotation measures (RMs), throughout the central regions of this source, with a strong asymmetry between the north and south lobes. Simple models for the high RMs are discussed and compared with the observations. To explain the north-south asymmetry in RM requires a magnetic field of strength ∼6 μG organized over a scale of ∼100 kpc. On smaller scales we find a tangled magnetic field with a strength of ∼30 μG