# Investigation of two Fermi-LAT gamma-ray blazars coincident with high-energy neutrinos detected by IceCube **Authors:** S. Garrappa, S. Buson, A. Franckowiak (Fermi-LAT collaboration), B. J., Shappee, J. F. Beacom, S. Dong, T. W.-S. Holoien, C. S. Kochanek, J. L., Prieto, K. Z. Stanek, T. A. Thompson (ASAS-SN collaboration), M. G. Aartsen,, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, M. Ahrens, C. Alispach, K., Andeen, T. Anderson, I. Ansseau, G. Anton, C. Arg\"uelles, J. Auffenberg, S., Axani, P. Backes, H. Bagherpour, X. Bai, A. Barbano, S. W. Barwick, V. Baum,, R. Bay, J. J. Beatty, K.-H. Becker, J. Becker Tjus, S. BenZvi, D. Berley, E., Bernardini, D. Z. Besson, G. Binder, D. Bindig, E. Blaufuss, S. Blot, C., Bohm, M. B\"orner, S. B\"oser, O. Botner, E. Bourbeau, J. Bourbeau, F., Bradascio, J. Braun, H.-P. Bretz, S. Bron, J. Brostean-Kaiser, A. Burgman, R., S. Busse, T. Carver, C. Chen, E. Cheung, D. Chirkin, K. Clark, L. Classen, G., H. Collin, J. M. Conrad, P. Coppin, P. Correa, D. F. Cowen, R. Cross, P., Dave, J. P. A. M. de Andr\'e, C. De Clercq, J. J. DeLaunay, H. Dembinski, K., Deoskar, S. De Ridder, P. Desiati, K. D. de Vries, G. de Wasseige, M. de, With, T. DeYoung, A. Diaz, J. C. D\'iaz-V\'elez, H. Dujmovic, M. Dunkman, E., Dvorak, B. Eberhardt, T. Ehrhardt, P. Eller, P. A. Evenson, S. Fahey, A. R., Fazely, J. Felde, K. Filimonov, C. Finley, A. Franckowiak, E. Friedman, A., Fritz, T. K. Gaisser, J. Gallagher, E. Ganster, S. Garrappa, L. Gerhardt, K., Ghorbani, T. Glauch, T. Gl\"usenkamp, A. Goldschmidt, J. G. Gonzalez, D., Grant, Z. Griffith, M. G\"under, M. G\"und\"uz, C. Haack, A. Hallgren, L., Halve, F. Halzen, K. Hanson, D. Hebecker, D. Heereman, K. Helbing, R., Hellauer, F. Henningsen, S. Hickford, J. Hignight, G. C. Hill, K. D. Hoffman,, R. Hoffmann, T. Hoinka, B. Hokanson-Fasig, K. Hoshina, F. Huang, M. Huber, K., Hultqvist, M. H\"unnefeld, R. Hussain, S. In, N. Iovine, A. Ishihara, E., Jacobi, G. S. Japaridze, M. Jeong, K. Jero, B. J. P. Jones, W. Kang, A., Kappes, D. Kappesser, T. Karg, M. Karl, A. Karle, U. Katz, M. Kauer, A., Keivani, J. L. Kelley, A. Kheirandish, J. Kim, T. Kintscher, J. Kiryluk, T., Kittler, S. R. Klein, R. Koirala, H. Kolanoski, L. K\"opke, C. Kopper, S., Kopper, D. J. Koskinen, M. Kowalski, K. Krings, G. Kr\"uckl, N. Kulacz, S., Kunwar, N. Kurahashi, A. Kyriacou, M. Labare, J. L. Lanfranchi, M. J. Larson,, F. Lauber, J. P. Lazar, K. Leonard, M. Leuermann, Q. R. Liu, E. Lohfink, C., J. Lozano Mariscal, L. Lu, F. Lucarelli, J. L\"unemann, W. Luszczak, J., Madsen, G. Maggi, K. B. M. Mahn, Y. Makino, K. Mallot, S. Mancina, I. C., Mari\c{s}, R. Maruyama, K. Mase, R. Maunu, K. Meagher, M. Medici, A. Medina,, M. Meier, S. Meighen-Berger, T. Menne, G. Merino, T. Meures, S. Miarecki, J., Micallef, G. Moment\'e, T. Montaruli, R. W. Moore, M. Moulai, R. Nagai, R., Nahnhauer, P. Nakarmi, U. Naumann, G. Neer, H. Niederhausen, S. C. Nowicki,, D. R. Nygren, A. Obertacke Pollmann, A. Olivas, A. O'Murchadha, E., O'Sullivan, T. Palczewski, H. Pandya, D. V. Pankova, N. Park, P. Peiffer, C., P\'erez de los Heros, D. Pieloth, E. Pinat, A. Pizzuto, M. Plum, P. B. Price,, G. T. Przybylski, C. Raab, A. Raissi, M. Rameez, L. Rauch, K. Rawlins, I. C., Rea, R. Reimann, B. Relethford, G. Renzi, E. Resconi, W. Rhode, M. Richman,, S. Robertson, M. Rongen, C. Rott, T. Ruhe, D. Ryckbosch, D. Rysewyk, I. Safa,, S. E. Sanchez Herrera, A. Sandrock, J. Sandroos, M. Santander, S. Sarkar, S., Sarkar, K. Satalecka, M. Schaufel, P. Schlunder, T. Schmidt, A. Schneider, J., Schneider, L. Schumacher, S. Sclafani, D. Seckel, S. Seunarine, M. Silva, R., Snihur, J. Soedingrekso, D. Soldin, M. Song, G. M. Spiczak, C. Spiering, J., Stachurska, M. Stamatikos, T. Stanev, A. Stasik, R. Stein, J. Stettner, A., Steuer, T. Stezelberger, R. G. Stokstad, A. St\"o{\ss}l, N. L. Strotjohann,, T. Stuttard, G. W. Sullivan, M. Sutherland, I. Taboada, F. Tenholt, S., Ter-Antonyan, A. Terliuk, S. Tilav, L. Tomankova, C. T\"onnis, S. Toscano, D., Tosi, M. Tselengidou, C. F. Tung, A. Turcati, R. Turcotte, C. F. Turley, B., Ty, E. Unger, M. A. Unland Elorrieta, M. Usner, J. Vandenbroucke, W. Van, Driessche, D. van Eijk, N. van Eijndhoven, S. Vanheule, J. van Santen, M., Vraeghe, C. Walck, A. Wallace, M. Wallraff, N. Wandkowsky, T. B. Watson, C., Weaver, M. J. Weiss, J. Weldert, C. Wendt, J. Werthebach, S. Westerhoff, B., J. Whelan, N. Whitehorn, K. Wiebe, C. H. Wiebusch, L. Wille, D. R. Williams,, L. Wills, M. Wolf, J. Wood, T. R. Wood, K. Woschnagg, G. Wrede, D. L. Xu, X., W. Xu, Y. Xu, J. P. Yanez, G. Yodh, S. Yoshida, T. Yuan (IceCube, collaboration) arXiv: 1901.10806 · 2019-08-07 ## TL;DR This study systematically analyzes gamma-ray blazars coincident with high-energy neutrinos, highlighting the potential of blazars like TXS 0506+056 and GB6 J1040+0617 as neutrino sources, but concluding most neutrino origins remain unidentified. ## Contribution It provides the first systematic multi-wavelength comparison of two gamma-ray blazars coincident with high-energy neutrinos, assessing their potential as neutrino sources. ## Key findings - TXS 0506+056 shows strong gamma-ray flux variability during neutrino detection. - GB6 J1040+0617's association with a neutrino is consistent with background expectations. - The majority of cosmic high-energy neutrinos likely originate from sources other than known gamma-ray blazars. ## Abstract After the identification of the gamma-ray blazar TXS 0506+056 as the first compelling IceCube neutrino source candidate, we perform a systematic analysis of all high-energy neutrino events satisfying the IceCube realtime trigger criteria. We find one additional known gamma-ray source, the blazar GB6 J1040+0617, in spatial coincidence with a neutrino in this sample. The chance probability of this coincidence is 30% after trial correction. For the first time, we present a systematic study of the gamma-ray flux, spectral and optical variability, and multi-wavelength behavior of GB6 J1040+0617 and compare it to TXS 0506+056. We find that TXS 0506+056 shows strong flux variability in the Fermi-LAT gamma-ray band, being in an active state around the arrival of IceCube-170922A, but in a low state during the archival IceCube neutrino flare in 2014/15. In both cases the spectral shape is statistically compatible ($\leq 2\sigma$) with the average spectrum showing no indication of a significant relative increase of a high-energy component. While the association of GB6 J1040+0617 with the neutrino is consistent with background expectations, the source appears to be a plausible neutrino source candidate based on its energetics and multi-wavelength features, namely a bright optical flare and modestly increased gamma-ray activity. Finding one or two neutrinos originating from gamma-ray blazars in the given sample of high-energy neutrinos is consistent with previously derived limits of neutrino emission from gamma-ray blazars, indicating the sources of the majority of cosmic high-energy neutrinos remain unknown. ## Full text _Full body text omitted from this summary view._ Fetch the complete paper as Markdown: https://tomesphere.com/paper/1901.10806/full.md ## Figures 11 figures with captions in the complete paper: https://tomesphere.com/paper/1901.10806/full.md ## References 105 references — full list in the complete paper: https://tomesphere.com/paper/1901.10806/full.md --- Source: https://tomesphere.com/paper/1901.10806