Evidence for Neutrino Emission from X-Ray-bright Active Galactic Nuclei with IceCube
R. Abbasi, M. Ackermann, J. Adams, Sanjib Kumar Agarwalla, J. A. Aguilar, M. Ahlers, Jean-Marco Alameddine, S. Ali, N. M. Amin, K. Andeen, C. Argüelles, Y. Ashida, S. Athanasiadou, Spencer Axani, R. Babu, X. Bai, J. Baines-Holmes, Aswathi Balagopal, S. W. Barwick, Simeon Bash, V. Basu, R. Bay, J. J. Beatty, J. Becker Tjus, Paul Behrens, Jakob Beise, Chiara Bellenghi, B. Benkel, S. BenZvi, D. Berley, E. Bernardini, D. Besson, E. Blaufuss, L. Bloom, S. Blot, Imre Bodó, F. Bontempo, Julia Book, Caterina Boscolo Meneguolo, S. Böser, O. Botner, J. Böttcher, J. Braun, Bennett Brinson, Zoe Brisson-Tsavoussis, Ryan T. Burley, Delaney Butterfield, Michael Campana, K. Carloni, Jose Carpio, Sharmistha Chattopadhyay, Thien Nhan Chau, Z. Chen, D. Chirkin, S. Choi, B. A. Clark, Alan Coleman, Peter John Cusack Coleman, G. H. Collin, Diego Alberto Coloma Borja, A. Connolly, J. M. Conrad, D. F. Cowen, C. De Clercq, James DeLaunay, D. Delgado, T. Delmeulle, Sen Deng, P. Desiati, K. D. de Vries, G. de Wasseige, T. DeYoung, J. C. Díaz–Vélez, Stephen DiKerby, Tianbing Ding, M. Dittmer, Alba Domi, Lincoln Draper, L. Dueser, Daniel Durnford, K. Dutta, M. A. DuVernois, T. Ehrhardt, Leonhard Eidenschink, A. Eimer, P. Eller, E. Ellinger, Dominik Elsässer, R. Engel, H. Erpenbeck, Waleed Esmail, S. Eulig, John Evans, P. A. Evenson, Kwok Lung Fan, Ke Fang, Kareem Ramadan Farrag, A. R. Fazely, A. Fedynitch, Nora Feigl
Abstract
Abstract Recently, IceCube reported neutrino emission from the Seyfert galaxy NGC 1068. Using 13.1 yr of IceCube data, we present a follow-up search for neutrino sources in the northern sky. NGC 1068 remains the most significant neutrino source among 110 preselected gamma-ray emitters while also being spatially compatible with the most significant location in the northern sky. Its energy spectrum is characterized by an unbroken power-law with spectral index γ = 3.4 ± 0.2. Consistent with previous results, the observed neutrino flux exceeds its gamma-ray counterpart by at least 2 orders of magnitude. Motivated by this disparity and the high X-ray luminosity of the source, we selected 47 X-ray-bright Seyfert galaxies from the Swift/BAT spectroscopic survey that were not included in the list of gamma-ray emitters. When testing this collection for neutrino emission, we observe a 3.3 σ excess from an ensemble of 11 sources, with NGC 1068 excluded from the sample. Our results strengthen the evidence that X-ray-bright cores of active galactic nuclei are neutrino emitters.