Cosmic 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 yr 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 gamma-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 gamma-ray emission and enlarges our view to potential new cosmic-ray acceleration sites.
Search for New Cosmic-Ray Acceleration Sites within the 4FGL Catalog Galactic Plane Sources / Abdollahi, S.; Acero, F.; Ackermann, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bellazzini, R.; Berenji, B.; Berretta, A.; Bissaldi, E.; Blandford, R. D.; Bonino, R.; Bruel, P.; Buson, S.; Cameron, R. A.; Caputo, R.; Caraveo, P. A.; Castro, D.; Chiaro, G.; Cibrario, N.; Ciprini, S.; Coronado-Bl??zquez, J.; Crnogorcevic, M.; Cutini, S.; D???ammando, F.; De Gaetano, S.; Di Lalla, N.; Dirirsa, F.; Di Venere, L.; Dom??nguez, A.; Fegan, S. J.; Fiori, A.; Fleischhack, H.; Franckowiak, A.; Fukazawa, Y.; Fusco, P.; Gammaldi, V.; Gargano, F.; Gasparrini, D.; Giacchino, F.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Green, D.; Grenier, I. A.; Grondin, M. -H.; Guiriec, S.; Gustafsson, M.; Harding, A. K.; Hays, E.; Hewitt, J. W.; Horan, D.; Hou, X.; J??hannesson, G.; Kayanoki, T.; Kerr, M.; Kuss, M.; Larsson, S.; Latronico, L.; Lemoine-Goumard, M.; Li, J.; Longo, F.; Loparco, F.; Lubrano, P.; Maldera, S.; Malyshev, D.; Manfreda, A.; Mart??-Devesa, G.; Mazziotta, M. N.; Mereu, I.; Michelson, P. F.; Mirabal, N.; Mitthumsiri, W.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Nuss, E.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Pei, Z.; Persic, M.; Pesce-Rollins, M.; Pillera, R.; Poon, H.; Porter, T. A.; Principe, G.; Rain??, S.; Rando, R.; Rani, B.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; S??nchez-Conde, M.; Saz Parkinson, P. M.; Scotton, L.; Serini, D.; Sgr??, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Sueoka, K.; Suson, D. J.; Tajima, H.; Tak, D.; Thayer, J. B.; Torres, D. F.; Troja, E.; Valverde, J.; Wadiasingh, Z.; Wood, K.; Zaharijas, G.. - In: THE ASTROPHYSICAL JOURNAL. - ISSN 1538-4357. - 933:2(2022), p. 204. [10.3847/1538-4357/ac704f]
Search for New Cosmic-Ray Acceleration Sites within the 4FGL Catalog Galactic Plane Sources
E. BissaldiMembro del Collaboration Group
;N. GigliettoMembro del Collaboration Group
;R. PilleraMembro del Collaboration Group
;
2022-01-01
Abstract
Cosmic 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 yr 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 gamma-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 gamma-ray emission and enlarges our view to potential new cosmic-ray acceleration sites.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
