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An Integral View of Fast Shocks around Supernova 1006.
Author/s: S. Nikolic, G. van de Ven, K. Heng, D. Kupko, B. Husemann, J. C. Raymond, J. P. Hughes,
Reference: 2013, Science DOI: 10.1126/science.1228297
VIMOS-IFU spectroscopy of the shock front in the remnant of SN 1006. The top-left panel shows a composite imageof the full remnant (≈30′ in diameter), combining data from the Very Large Array and Green Bank Telescope (red;NRAO/AUI/NSF/GBT/VLA/Dyer, Maddalena & Cornwell), Chandra X-ray Observatory (blue; NASA/CXC/Rutgers/G.Cassam-Chena¨ı, J. Hughes et al.), 0.9m Curtis Schmidt optical telescope (yellow;NOAO/AURA/NSF/CTIO/Middlebury College/F. Winkler), and Digitized Sky Survey (orange and light blue stars).The green box indicates the region covered by the Hubble Space Telescope (HST) H narrow-band image shown in thetop-middle, with subsequently the magenta box indicating the region observed with the VIMOS-IFU. The top-rightpanel shows the reduced datacube collapsed in wavelength around the H-line, recovering the shock front. Thecrosses with four different colors indicate the pixels for which the spectra have been combined to produce thespectra shown in the four panels at the bottom. In each of the bottom panels, the dashed black lines show the best-fitdouble-Gaussian, with parameters given in the legenda: the intensity ratio of the broad to narrow component Ib=In,the velocity offset between the broad and narrow line centroids ΔV (in km s−1), and width of the broad component W(in km s−1). The reduced 2 values above unity along with the differences between the observed spectra and theirbest-fits (shown below the spectra with an offset of -0.3 for clarity), indicate that non-Gaussianity is present. Most ofthe reduced 2 values above unity come from the mismatching near the line core, as can be seen from the zoomed-inregion (-1000,1000) km s−1 in the top-right corner of bottom panels. On the horizontal axis is shown only the fittedregion of the spectra, while the y axis shows the flux in units of 10−16 erg s−1 cm−2 Å−1 rescaled with the respect tothe blue panel by factors 2 and 0.5 for the yellow and red panel, respectively.
Supernova remnants are among the most spectacular examples of astrophysical pistons in our cosmic neighborhood. The gas expelled by the supernova explosion is launched with velocities ∼1000 km/s into the ambient, tenuous interstellar medium, producing shocks that excite hydrogen lines. We have used an optical integral-field spectrograph to obtain high-resolution spatial-spectral maps that allow us to study in detail the shocks in the northwestern rim of supernova 1006. The two-component Halpha line is detected at 133 sky locations. Variations in the broad line widths and the broad-to-narrow line intensity ratios across tens of atomic mean free paths suggest the presence of suprathermal protons, the potential seed particles for generating high-energy cosmic-rays.