Discovery of Kolmogorov-like Turbulence in the Inner Shell of the Supernova Remnant HB 9

We investigated the scaling relation of the magnetohydrodynamic turbulence in the inner and outer shells of the supernova remnant HB 9 using multitracers. For the eastern inner shell section, 1D structure function and power spectrum analyses of the radio total intensity, H α emission, and polarized intensity consistently show a Kolmogorov-like scaling l 2/3 over the inertial range. The 2D power spectrum for the entire inner region follows k −8/3 of all tracers, including the polarization gradient ∇ P . It indicates that fully developed, trans-Alfvénic Kolmogorov turbulence is present in the inner shell of HB 9. We estimated the strength of the random magnetic field therein from the low fractional polarization (∼5%) and obtained an upper limit of δB ∼ 18 μ G. The turbulence in the inner shock shell is most likely driven by the Richtmyer–Meshkov instability.