학술논문
Investigation of Two Fermi-LAT Gamma-Ray Blazars Coincident with High-energy Neutrinos Detected by IceCube
Document Type
article
Author
Garrappa, S; Buson, S; Franckowiak, A; Shappee, BJ; Beacom, JF; Dong, S; Holoien, TW-S; Kochanek, CS; Prieto, JL; Stanek, KZ; Thompson, TA; Aartsen, MG; Ackermann, M; Adams, J; Aguilar, JA; Ahlers, M; Ahrens, M; Alispach, C; Andeen, K; Anderson, T; Ansseau, I; Anton, G; Argüelles, C; Auffenberg, J; Axani, S; Backes, P; Bagherpour, H; Bai, X; Barbano, A; Barwick, SW; Baum, V; Bay, R; Beatty, JJ; Becker, K-H; Tjus, J Becker; BenZvi, S; Berley, D; Bernardini, E; Besson, DZ; Binder, G; Bindig, D; Blaufuss, E; Blot, S; Bohm, C; Börner, M; Böser, S; Botner, O; Bourbeau, E; Bourbeau, J; Bradascio, F; Braun, J; Bretz, H-P; Bron, S; Brostean-Kaiser, J; Burgman, A; Busse, RS; Carver, T; Chen, C; Cheung, E; Chirkin, D; Clark, K; Classen, L; Collin, GH; Conrad, JM; Coppin, P; Correa, P; Cowen, DF; Cross, R; Dave, P; de André, JPAM; De Clercq, C; DeLaunay, JJ; Dembinski, H; Deoskar, K; De Ridder, S; Desiati, P; de Vries, KD; de Wasseige, G; de With, M; DeYoung, T; Diaz, A; Díaz-Vélez, JC; Dujmovic, H; Dunkman, M; Dvorak, E; Eberhardt, B; Ehrhardt, T; Eller, P; Evenson, PA; Fahey, S; Fazely, AR; Felde, J; Filimonov, K; Finley, C; Friedman, E; Fritz, A; Gaisser, TK; Gallagher, J; Ganster, E
Source
The Astrophysical Journal. 880(2)
Subject
Language
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 multiwavelength 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-Large Area Telescope 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 (≤2σ) 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 multiwavelength 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.