Batchelor, Saffman, and Kazantsev spectra in galactic small-scale dynamos

ABSTRACT The magnetic fields in galaxy clusters and probably also the interstellar medium are believed to be generated by a small-scale dynamo. Theoretically, during its kinematic stage, it is characterized Kazantsev spectrum, which peaks at resistive scale. It only slightly shallower than Saffman spectrum that expected for random causally connected fields. Causally disconnected have even steeper Batchelor spectrum. Here, we show all three spectra present During occurs on scales larger energy-carrying scale of turbulence, smaller within inertial range turbulence – Prandtl number unity. In saturated state, dynamo develops large scales, suggestive build-up long-range correlations. At numbers, elongated structures seen synthetic synchrotron emission maps showing parity-even E polarization. We observe significant excess polarization over parity-odd B subresistive deficiency scales. This finding odds with observed Galactic microwave foreground emission, associated polarizations may highly non-Gaussian skewed regime For dust however, polarized always nearly Gaussian, much weaker.