Both observations and simulations reveal large inhomogeneities in magnetic field distributions in diffuse plasmas. Incorporating these inhomogeneities into various calculations can significantly change the inferred physical conditions. In extragalactic sources, e. g., these can compromise analyses of spectral ageing, which I will illustrate with some current work on cluster relics. I also briefly re-examine the old issue of how inhomogeneous fields affect particle lifetimes; perhaps not surprisingly, the next generation of radio telescopes are unlikely to find many sources that can extend their lifetimes from putting relativistic electrons into a low-field 'freezer'. Finally, I preview some new EVLA results on the complex relic in Abell 2256, with implications for the interspersing of its relativistic and thermal plasmas.
Bibliographical noteFunding Information:
This work is supported, in part, by U.S. National Science Foundation grant AST-0908688 to the University of Minnesota. The National Radio Astronomy Observatory/EVLA is operated by Assoc. Univ. Inc. under co-operative agreement with the U.S. National Science Foundation.
- Radiation mechanisms: nonthermal
- galaxies: clusters
- magnetic fields