Abdollahi, S.Acero, F.Ackermann, M.Baldini, L.Mirabal, NestorJanethet al2022-06-092022-06-092022-07-14Abdollahi, S. et al. "Search for New Cosmic-Ray Acceleration Sites within the 4FGL Catalog Galactic Plane Sources." The Astrophysical Journal, 933, no. 2 (2022 July 14). https://doi.org/10.3847/1538-4357/ac704fhttp://hdl.handle.net/11603/24885https://doi.org/10.3847/1538-4357/ac704fAuthors: S. Abdollahi , F. Acero , M. Ackermann , L. Baldini , J. Ballet*, G. Barbiellini,, D. Bastieri,, , R. Bellazzini, B. Berenji, A. Berretta, E. Bissaldi,, R. D. Blandford, R. Bonino,, P. Bruel , S. Buson, R. A. Cameron, R. Caputo, P. A. Caraveo, D. Castro,, G. Chiaro, N. Cibrario , S. Ciprini,, J. Coronado-Blazquez ´ ,, M. Crnogorcevic, S. Cutini, F. D’Ammando, S. De Gaetano , N. Di Lalla, F. Dirirsa, L. Di Venere,, A. Dom´ınguez, S. J. Fegan, A. Fiori, H. Fleischhack,, , A. Franckowiak, Y. Fukazawa, P. Fusco,, V. Gammaldi, F. Gargano, D. Gasparrini, , F. Giacchino,, N. Giglietto,, F. Giordano,, M. Giroletti, T. Glanzman, D. Green, I. A. Grenier , M.-H. Grondin, S. Guiriec,, M. Gustafsson, A. K. Harding, E. Hays, J.W. Hewitt, D. Horan , X. Hou,,, G. Johannesson ´ ,, T. Kayanoki, M. Kerr, M. Kuss, S. Larsson,,, L. Latronico , M. Lemoine-Goumard*, J. Li,, F. Longo,, F. Loparco,, P. Lubrano, S. Maldera, D. Malyshev , A. Manfreda , G. Mart´ı-Devesa , M. N. Mazziotta, I.Mereu,, P. F. Michelson, N. Mirabal, , W. Mitthumsiri, T. Mizuno, M. E. Monzani, A. Morselli, I. V. Moskalenko, E. Nuss, N. Omodei , M. Orienti, E. Orlando,, J. F. Ormes, D. Paneque, Z. Pei , M. Persic,, M. Pesce-Rollins , R. Pillera,, H. Poon, T. A. Porter, G. Principe,,, S. Raino` ,, R. Rando,,, B. Rani,, , M. Razzano , S. Razzaque, A. Reimer,, O. Reimer, T. Reposeur*, M. Sanchez-Conde ´ , , P. M. Saz Parkinson,,, L. Scotton, D. Serini, C. Sgro` , E. J. Siskind, G. Spandre, P. Spinelli, , K. Sueoka, D. J. Suson, H. Tajima,, D. Tak,, J. B. Thayer, D. F. Torres,, E. Troja, , J. Valverde,, Z. Wadiasingh, K. Wood, G. ZaharijasCosmic rays are mostly composed of protons accelerated to relativistic speeds. When those protons encounter interstellar material, they produce neutral pions which in turn decay into gamma rays. This offers a compelling way to identify the acceleration sites of protons. A characteristic hadronic spectrum, with a low-energy break around 200 MeV, was detected in the gamma-ray spectra of four Supernova Remnants (SNRs), IC 443, W44, W49B and W51C, with the Fermi Large Area Telescope. This detection provided direct evidence that cosmic-ray protons are (re-)accelerated in SNRs. Here, we present a comprehensive search for low-energy spectral breaks among 311 4FGL catalog sources located within 5◦ from the Galactic plane. Using 8 years of data from the Fermi Large Area Telescope between 50 MeV and 1 GeV, we find and present the spectral characteristics of 56 sources with a spectral break confirmed by a thorough study of systematic uncertainty. Our population of sources includes 13 SNRs for which the proton-proton interaction is enhanced by the dense target material; the high-mass γ-ray binary LS I +61 303; the colliding wind binary η Carinae; and the Cygnus star-forming region. This analysis better constrains the origin of the γ-ray emission and enlarges our view to potential new cosmic-ray acceleration sites.29 pagesen-USThis work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.Public Domain Mark 1.0Text