Orateur
Mme
Sladjana Nikolic
(MPIA Heidelberg)
Description
Supernova remnants are laboratories for studying optical shocks. Shocks with velocities of a few hundred km/s (or more) produce two-component Hα lines: a narrow spike atop a broad base. The widths of these lines serve as thermometers for the pre- and post-shock ambient interstellar medium, the ratio of the line strengths is a diagnostic for plasma conditions in the shock, and the offset between the centroids of the lines indicate the geometry of the shocks away from edge-on viewing. Moreover, investigating in detail the shape of the Hα-line has the potential to provide observational constrains on cosmic ray (CR) acceleration.
Observing the north-eastern rim in the supernova remnant of SN1006 with the VIMOS-IFU spectrograph on the VLT, we show that such spectroscopic imaging techniques allow us to trace and distinguish multiple, projected shocks, and at the same time provide us in detail the Hα line profile at each position. By fitting these profiles, we extract maps of the broad and narrow line width, the broad-to-narrow line ratio, as well as velocity offsets between broad and narrow line centroids. We find that all four quantities vary as function of position along and perpendicular to the shock fronts, indicating changing geometry and plasma conditions, as well as presence of CRs. The detection of significant deviations from a (double) Gaussian Hα line profile further supports the presence and acceleration of CRs in SN1006.
