Spectrum and polarization of radio galaxy lobes and tails.

The distribution of radio spectra across six radio galaxies is studied at ≡4arcmin resolution. Spectral breaks consistent with the absence of particle acceleration are rare, and spectra do not always show the expected steepening with core distance or with frequency. Even in far outer tails there is evidence for recent reacceleration. Spectral flattening often occurs near bends, wiggles, and knots; thus, particle acceleration seems most efficient at "working surfaces" with the ambient media. Radio spectra indicate an energy spectrum of the accelerated particles flatter than ≡E^-1.6 in these areas. Some polarization maps reveal inverted depolarization and departures from the λ² law of Faraday rotation, probably due to different physical regimes within one antenna beam.