Supernova W44 & IC 443 Neutral Pion Decay Spectral Fit (image) DOE/SLAC National Accelerator Laboratory Share Print E-Mail 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 Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.