Fig. 4: Ionization parameter and post-shock density.
From: The supernova remnant SN 1006 as a Galactic particle accelerator
68%, 90%, and 99% confidence contour levels of the ISM density and ionization parameter derived from the Chandra spectra of region 0 (a) and region 5 (b). Red and blue lines mark isochrones after the interaction with the shock front.
