Detection of the Characteristic Pion-Decay Signature in Supernova Remnants. Fermi LAT collaboration
Document Type
Article
Publication Date
2013
Abstract
Cosmic rays are particles (mostly protons) accelerated to relativistic speeds. Despite wide agreement that supernova remnants (SNRs) are the sources of galactic cosmic rays, unequivocal evidence for the acceleration of protons in these objects is still lacking. When accelerated protons encounter interstellar material, they produce neutral pions, which in turn decay into gamma rays. This offers a compelling way to detect the acceleration sites of protons. The identification of pion-decay gamma rays has been difficult because high-energy electrons also produce gamma rays via bremsstrahlung and inverse Compton scattering. We detected the characteristic pion-decay feature in the gamma-ray spectra of two SNRs, IC 443 and W44, with the Fermi Large Area Telescope. This detection provides direct evidence that cosmic-ray protons are accelerated in SNRs.
Publication Title
Science Magazine
Volume
339
First Page
807
Digital Object Identifier (DOI)
https://doi.org/10.1126/science.1231160
Citation Information
Hewitt, J.W., Ackermann, M., Baldini, L., Bechtol, K., Bellazzini, R., Blandford, R. D., Borgland, A. W., Bottacini, E., Brandt, T. J., Bregeon, J., Brigida, M., Bruel, P., Busetto, G., Buson, S., Cameron, et. al. (2013). Detection of the Characteristic Pion-Decay Signature in Supernova Remnants. Science Magazine, 339, 807. https://doi.org/10.48550/arxiv.1302.3307