2007MNRAS.382...67T

We present high-resolution images of the Faraday rotation measure (RM) structure of the radio galaxy PKS1246-410at the centre of the Centaurus cluster. Comparison with Hα-line and soft X-ray emission reveals a correspondence between the line-emitting gas, the soft X-ray emitting gas, regions with an excess in the RM images and signs of depolarization. Magnetic field strengths of 25 µG, organized on scales of ∼1 kpc and intermixed with gas at a temperature of 5x10⁶K with a density of ∼0.1/cm3, can reproduce the observed RM excess, the depolarization and the observed X-ray surface brightness. This hot gas may be in pressure equilibrium with the optical line-emitting gas, but the magnetic field strength of 25 µG associated with the hot gas provides only 10 per cent of the thermal pressure and is therefore insufficient to account for the stability of the line-emitting filaments.