Shock-cloud interaction and particle acceleration in the southwestern limb of SN 1006 – Marco Miceli (INAF – Osservatorio Astronomico di Palermo )

The supernova remnant SN 1006 is a powerful source of high-energy particles and evolves in a tenuous and uniform environment. The X-ray image of SN 1006 reveals an indentation in the southwestern part of the shock front and the HI maps show an isolated cloud (hereafter southwestern cloud) whose morphology fits perfectly in the indentation. We performed spatially resolved spectral analysis of a set of small regions in the southwestern nonthermal limb. We also analyzed archive HI data, obtained combining single dish and interferometric observations. We found that the best-fit value of the NH derived from the X-ray spectra significantly increases in regions corresponding to the southwestern cloud, while the cutoff energy of the synchrotron emission decreases. The amount of the NH variations corresponds perfectly with the column density of the southwestern cloud, as estimated from the radio data. The decrease in the cutoff energy at the indentation clearly reveals that the cloud is actually interacting with the remnant. The presence of a dense environment near a region where efficient particle acceleration is at work makes the southwestern limb a promising source of gamma-ray hadronic emission. We estimate that such emission will be detectable with the Fermi telescope within a few years.