ANTARES constrains a blazar origin of two IceCube PeV neutrino events^⋆

¹ Institut d’Investigació per a la Gestió Integrada de les Zones Costaneres (IGIC) – Universitat Politècnica de València. C/ Paranimf 1, 46730 Gandia, Spain
² GRPHE – Université de Haute Alsace – Institut Universitaire de Technologie de Colmar, 34 rue du Grillenbreit, BP 50568, 68008 Colmar, France
³ Technical University of Catalonia, Laboratory of Applied Bioacoustics, Rambla Exposició, 08800 Vilanova i la Geltrú, Barcelona, Spain
⁴ INFN–Sezione di Genova, via Dodecaneso 33, 16146 Genova, Italy
⁵ Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen Centre for Astroparticle Physics, Erwin-Rommel-Str. 1, 91058 Erlangen, Germany
⁶ CPPM, Aix-Marseille Université, CNRS/IN2P3, 13009 Marseille, France
⁷ APC, Université Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cité, 75205 Paris, France
⁸ IFIC – Instituto de Física Corpuscular, Edificios Investigación de Paterna, CSIC – Universitat de València, Apdo. de Correos 22085, 46071 Valencia, Spain
⁹ LAM – Laboratoire d’Astrophysique de Marseille, Pôle de l’Étoile Site de Château-Gombert, rue Frédéric Joliot-Curie 38, 13388 Marseille Cedex 13, France
¹⁰ INFN–Sezione di Bologna, viale Berti-Pichat 6/2, 40127 Bologna, Italy
¹¹ Dipartimento di Fisica e Astronomia dell’Università, Viale Berti-Pichat 6/2, 40127 Bologna, Italy
¹² Nikhef, Science Park, 1098 XG Amsterdam, The Netherlands
¹³ Huygens-Kamerlingh Onnes Laboratorium, Universiteit Leiden, 2300 RA Leiden, The Netherlands
¹⁴ Universiteit van Amsterdam, Instituut voor Hoge-Energie Fysica, Science Park 105, 1098 XG Amsterdam, The Netherlands
¹⁵ INFN–Sezione di Roma, P.le Aldo Moro 2, 00185 Roma, Italy
¹⁶ Dipartimento di Fisica dell’Università La Sapienza, P.le Aldo Moro 2, 00185 Roma, Italy
¹⁷ Institute for Space Science, 077125 Bucharest, Măgurele, Romania
¹⁸ INFN–Sezione di Bari, via E. Orabona 4, 70126 Bari, Italy
¹⁹ INFN–Sezione di Napoli, via Cintia 80126 Napoli, Italy
²⁰ Dipartimento di Fisica dell’Università Federico II di Napoli, via Cintia 80126 Napoli, Italy
²¹ Mediterranean Institute of Oceanography (MIO), Aix-Marseille University, 13288 Marseille, Cedex 9, France
²² Université du Sud Toulon-Var, CNRS-INSU/IRD UM 110, 83957 La Garde Cedex, France
²³ Géoazur, Université Nice Sophia-Antipolis, CNRS/INSU, IRD, Observatoire de la Côte d’Azur, Sophia Antipolis, France
²⁴ INFN–Laboratori Nazionali del Sud (LNS), via S. Sofia 62, 95123 Catania, Italy
²⁵ Univ. Paris-Sud , 91405 Orsay Cedex, France
²⁶ Kernfysisch Versneller Instituut (KVI), University of Groningen, Zernikelaan 25, 9747 AA Groningen, The Netherlands
²⁷ Laboratoire de Physique Corpusculaire, Clermont Université, Université Blaise Pascal, CNRS/IN2P3, BP 10448, 63000 Clermont-Ferrand, France
²⁸ INFN–Sezione di Catania, viale Andrea Doria 6, 95125 Catania, Italy
²⁹ Royal Netherlands Institute for Sea Research (NIOZ), Landsdiep 4, 1797 SZ ’t Horntje (Texel), The Netherlands
³⁰ Universiteit Utrecht, FaculteitBetawetenschappen, Princetonplein 5, 3584 CC Utrecht, The Netherlands
³¹ Dr. Remeis-Sternwarte and ECAP, Universität Erlangen-Nürnberg, Sternwartstr. 7, 96049 Bamberg, Germany
³² Dipartimento di Fisica ed Astronomia dell’Università, viale Andrea Doria 6, 95125 Catania, Italy
³³ Direction des Sciences de la Matière – Institut de recherche sur les lois fondamentales de l’Univers – Service de Physique des Particules, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
³⁴ IPHC-Institut Pluridisciplinaire Hubert Curien – Université de Strasbourg et CNRS/IN2P3, 23 rue du Loess, BP 28, 67037 Strasbourg Cedex 2, France
³⁵ ITEP – Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow, Russia
³⁶ Dipartimento di Fisica dell’Università, via Dodecaneso 33, 16146 Genova, Italy
³⁷ University Mohammed I, Laboratory of Physics of Matter and Radiations, BP 717, 6000 Oujda, Morocco
³⁸ Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Emil-Fischer-Str. 31, 97074 Würzburg, Germany
³⁹ NASA, Goddard Space Flight Center, Greenbelt, MD 20771, USA
⁴⁰ University of Maryland, Baltimore County, Baltimore, MD 21250, USA
⁴¹ Catholic University of America, Washington, DC 20064, USA
⁴² Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁴³ Departament d’Astronomia i Astrofísica, Universitat de València, C/ Dr. Moliner 50, 46100 Burjassot, València, Spain
⁴⁴ Observatori Astronòmic, Universitat de València, C/ Catedrático José Beltrán No. 2, 46980 Paterna, València, Spain
⁴⁵ Departamento de Astronomía, Universidad de Concepción, Casilla 160, Chile
⁴⁶ CSIRO Astronomy and Space Science, ATNF, PO Box 76 Epping, NSW 1710, Australia
⁴⁷ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85741 Garching, Germany
⁴⁸ Bundesamt für Kartographie und Geodäsie, 93444 Bad Kötzting, Germany
⁴⁹ CSIRO Astronomy and Space Science, Canberra Deep Space Communications Complex, PO Box 1035, Tuggeranong, ACT 2901, Australia
⁵⁰ School of Mathematics & Physics, University of Tasmania, Private Bag 37, Hobart, Tasmania 7001, Australia
⁵¹ Hartebeesthoek Radio Astronomy Observatory, 1740 Krugersdorp, South Africa

^⋆⋆ Corresponding authors: C. W James, e-mail: clancy.james@physik.uni-erlangen.de; M. Kadler, e-mail: kadler@physik.uni-wuerzburg.de

Received: 15 January 2015
Accepted: 23 February 2015

Abstract

Context. The source(s) of the neutrino excess reported by the IceCube Collaboration is unknown. The TANAMI Collaboration recently reported on the multiwavelength emission of six bright, variable blazars which are positionally coincident with two of the most energetic IceCube events. Objects like these are prime candidates to be the source of the highest-energy cosmic rays, and thus of associated neutrino emission.

Aims. We present an analysis of neutrino emission from the six blazars using observations with the ANTARES neutrino telescope.

Methods. The standard methods of the ANTARES candidate list search are applied to six years of data to search for an excess of muons – and hence their neutrino progenitors – from the directions of the six blazars described by the TANAMI Collaboration, and which are possibly associated with two IceCube events. Monte Carlo simulations of the detector response to both signal and background particle fluxes are used to estimate the sensitivity of this analysis for different possible source neutrino spectra. A maximum-likelihood approach, using the reconstructed energies and arrival directions of through-going muons, is used to identify events with properties consistent with a blazar origin.

Results. Both blazars predicted to be the most neutrino-bright in the TANAMI sample (1653−329 and 1714−336) have a signal flux fitted by the likelihood analysis corresponding to approximately one event. This observation is consistent with the blazar-origin hypothesis of the IceCube event IC 14 for a broad range of blazar spectra, although an atmospheric origin cannot be excluded. No ANTARES events are observed from any of the other four blazars, including the three associated with IceCube event IC20. This excludes at a 90% confidence level the possibility that this event was produced by these blazars unless the neutrino spectrum is flatter than −2.4.