The Faraday rotation of Cygnus A - Magnetic fields in cluster gas

摘要: Multifrequency, multiconfiguration observations with the VLA have allowed, for first time, detailed mapping of rotation measure (RM) prominent extragalactic radio source Cygnus A. It is found that this lies behind a deep Faraday screen, varying from -4000 to +3000 rad/sq m eastern lobe, and -2000 +1500 western lobe. Gradients in both lobes commonly exceed 300 m/arcsec. The overall pattern RM same each increasing east west, leading conclusion magnetic field ordered on scales about 20 30 kpc. There no evidence internal depolarization. authors examine, reject, hypothesis screen has Galactic origin propose its intracluster gas which A embedded. 66 references.