Ackermann M, Ajello M, Albert A, Allafort A, Atwood WB, Baldini L, Ballet J, Barbiellini G, Bastieri D, Bechtol K, Bellazzini R, Bloom ED, Bonamente E, Bottacini E, Brandt TJ, Bregeon J, Brigida M, Bruel P, Buehler R, Buson S, Caliandro GA, Cameron RA, Caraveo PA, Cavazzuti E, Chaves RCG, Chiang J, Chiaro G, Ciprini S, Claus R, Cohen-Tanugi J, Conrad J, D'Ammando F, de Angelis A, de Palma F, Dermer CD, Digel SW, Drell PS, Drlica-Wagner A, Favuzzi C, Franckowiak A, Funk S, Fusco P, Gargano F, Gasparrini D, Germani S, Giglietto N, Giordano F, Giroletti M, Godfrey G, Gomez-Vargas GA, Grenier IA, Guiriec S, Gustafsson M, Hadasch D, Hayashida M, Hewitt J, Hughes RE, Jeltema TE, Johannesson G, Johnson AS, Kamae T, Kataoka J, Knoedlseder J, Kuss M, Lande J, Larsson S, Latronico L, Garde ML, Longo F, Loparco F, Lovellette MN, Lubrano P, Mayer M, Mazziotta MN, McEnery JE, Michelson PF, Mitthumsiri W, Mizuno T, Monzani ME, Morselli A, Moskalenko IV, Murgia S, Nemmen R, Nuss E, Ohsugi T, Orienti M, Orlando E, Ormes JF, Perkins JS, Pesce-Rollins M, Piron F, Pivato G, Raino S, Rando R, Razzano M, Razzaque S, Reimer A, Reimer O, Ruan J, Sanchez-Conde M, Schulz A, Sgro C, Siskind EJ, Spandre G, Spinelli P, Storm E, Strong AW, Suson DJ, Takahashi H, Thayer JG, Thayer JB, Thompson DJ, Tibaldo L, Tinivella M, Torres DF, Troja E, Uchiyama Y, Usher TL, Vandenbroucke J, Vianello G, Vitale V, Winer BL, Wood KS, Zimmer S, Pinzke A, Pfrommer C (2014)
Publication Status: Published
Publication Type: Journal article
Publication year: 2014
Publisher: American Astronomical Society
Book Volume: 787
DOI: 10.1088/0004-637X/787/1/18
Current theories predict relativistic hadronic particle populations in clusters of galaxies in addition to the already observed relativistic leptons. In these scenarios hadronic interactions give rise to neutral pions which decay into gamma rays that are potentially observable with the Large Area Telescope (LAT) on board the Fermi space telescope. We present a joint likelihood analysis searching for spatially extended gamma-ray emission at the locations of 50 galaxy clusters in four years of Fermi-LAT data under the assumption of the universal cosmic-ray (CR) model proposed by Pinzke & Pfrommer. We find an excess at a significance of 2.7 sigma, which upon closer inspection, however, is correlated to individual excess emission toward three galaxy clusters: A400, A1367, and A3112. We discuss these cases in detail and conservatively attribute the emission to unmodeled background systems (for example, radio galaxies within the clusters). Through the combined analysis of 50 clusters, we exclude hadronic injection efficiencies in simple hadronic models above 21% and establish limits on the CR to thermal pressure ratio within the virial radius, R-200, to be below 1.25%-1.4% depending on the morphological classification. In addition, we derive new limits on the gamma-ray flux from individual clusters in our sample.
APA:
Ackermann, M., Ajello, M., Albert, A., Allafort, A., Atwood, W.B., Baldini, L.,... Pfrommer, C. (2014). SEARCH FOR COSMIC-RAY-INDUCED GAMMA-RAY EMISSION IN GALAXY CLUSTERS. Astrophysical Journal, 787. https://doi.org/10.1088/0004-637X/787/1/18
MLA:
Ackermann, M., et al. "SEARCH FOR COSMIC-RAY-INDUCED GAMMA-RAY EMISSION IN GALAXY CLUSTERS." Astrophysical Journal 787 (2014).
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