Radiative instability in synchrotron-emitting plasmas

We present a linear study of the radiative instability driven by synchrotron emission in astrophysical plasmas. The novelty in this work is to consider the case of a non-Maxwellian distribution function and follow its time evolution consistently. We find unstable filamentation modes for any value of the spectral index, with increasing growth rate going from steep to flat spectra, provided that the plasma beta is larger than unity. We discuss our results in the context of the formation of the filamentary structures observed in jets and lobes of extended radio sources.