fronts required to generate ultra-high energy cosmic rays. Observation of the SN 1006 remnant in the X-ray has shown synchrotron emission consistent with it being a source of cosmic rays. However, for energies higher than about 1018 eV a different mechanism is required as supernova remnants cannot provide sufficient energy. It is still unclear whether supernova remnants accelerate cosmic rays up to PeV energies. The future telescope CTA will help to answer this question. See also References External links List of All Known Galactic and Extragalactic Supernovae on the Open Supernova Catalog (these are not supernova remnants yet) Galactic SNR Catalogue (D. A. Green, University of Cambridge) Chandra observations of supernova remnants: catalog, photo album, selected picks 2MASS images of Supernova Remnants NASA: Introduction to Supernova Remnants NASA's Imagine: Supernova Remnants Afterlife of a Supernova on UniverseToday.com Supernova remnant on arxiv.org Supernova Remnants, SEDS Remnants Nebulae ja:超新星#超新星残骸