Contact: Andy Freeberg
DOE/SLAC National Accelerator Laboratory
Caption: Finding evidence for the acceleration of protons has long been a key issue in the efforts to explain the origin of cosmic rays. This pair of spectra from two supernova remnants (also shown visibly with data from various satellites and wavelengths) are the "smoking gun" that researchers have been looking for. The Fermi Large Area Telescope's observations fit very neatly with predictions of neutral pion decay.
Credit: NASA/DOE/Fermi LAT Collaboration, Chandra X-ray Observatory, ESA Herschel/XMM-Newton
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