Multiwavelength follow-up of a rare IceCube neutrino multiplet

¹ III. Physikalisches Institut, RWTH Aachen University, 52056 Aachen, Germany
² Department of Physics, University of Adelaide, Adelaide 5005, Australia
³ Dept of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131, USA
⁴ Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645, USA
⁵ Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA
⁶ Dept. of Physics and Astronomy, University of Alaska Anchorage, 3211 Providence Dr., Anchorage, AK 99508, USA
⁷ CTSPS, Clark-Atlanta University, Atlanta, GA 30314, USA
⁸ School of Physics and Center for Relativistic Astrophysics, Georgia Institute of Technology, Atlanta, GA 30332, USA
⁹ Dept. of Physics, Southern University, Baton Rouge, LA 70813, USA
¹⁰ Department of Physics and Center for Astrophysics, Tsinghua University, Beijing 100084, PR China
¹¹ Dept. of Physics, University of California, Berkeley, CA 94720, USA
¹² Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
¹³ Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
¹⁴ Fakultät für Physik & Astronomie, Ruhr-Universität Bochum, 44780 Bochum, Germany
¹⁵ Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn, Germany
¹⁶ Université Libre de Bruxelles, Science Faculty CP230, 1050 Brussels, Belgium
¹⁷ Vrije Universiteit Brussel, Dienst ELEM, 1050 Brussels, Belgium
¹⁸ Dept. of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
¹⁹ Instituto de Astronomía, Universidad Nacional Autónoma de México, Ciudad de Mexico, Mexico
²⁰ Instituto de Física, Universidad Nacional Autónoma de México, Ciudad de Mexico, Mexico
²¹ Instituto de Geofísica, Universidad Nacional Autónoma de México, Ciudad de Mexico, Mexico
²² Centro de Investigación en Computación, Instituto Politécnico Nacional, México City, Mexico
²³ Physics Department, Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, DF, Mexico
²⁴ Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de Mexico, Ciudad de Mexico, Mexico
²⁵ Universidad Autónoma de Chiapas, Tuxtla Gutiérrez, Chiapas, Mexico
²⁶ Dept. of Physics and Institute for Global Prominent Research, Chiba University, Chiba 263-8522, Japan
²⁷ Enrico Fermi Institute, University of Chicago, Chicago, IL 60637, USA
²⁸ Dept. of Physics and Astronomy, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
²⁹ Dept. of Physics, University of Maryland, College Park, MD 20742, USA
³⁰ Dept. of Physics and Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210, USA
³¹ Dept. of Astronomy, Ohio State University, Columbus, OH 43210, USA
³² Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
³³ Department of Physical Sciences, Cork Institute of Technology, Bishopstown, Cork, Ireland
³⁴ Department of Physics, University of California, 1 Shields Ave, Davis, CA 95616-5270, USA
³⁵ Dept. of Physics, TU Dortmund University, 44221 Dortmund, Germany
³⁶ School of Physics, University College Dublin, Belfield, Dublin 4, Ireland
³⁷ Dept. of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
³⁸ Dept. of Physics, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
³⁹ Einstein Fellow  
⁴⁰ Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
⁴¹ School of Physics, Astronomy, and Computational Sciences, George Mason University, Fairfax, VA, USA
⁴² School of Physics, National University ofIreland Galway, University Road, Galway, Ireland
⁴³ Département de physique nucléaire et corpusculaire, Université de Genève, 1211 Genève, Switzerland
⁴⁴ Dept. of Physics and Astronomy, University of Gent, 9000 Gent, Belgium
⁴⁵ Las Cumbres Observatory, 6740 Cortona Dr, Ste 102, Goleta, CA 93117-5575, USA
⁴⁶ Instituto de Astrofísica de Andalucía (IAA-CSIC), Glorieta de la Astronomía s/n, 18008 Granada, Spain
⁴⁷ NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771, USA
⁴⁸ Department of Physics and Astronomy, DePauw University, Greencastle, IN 46135-0037, USA
⁴⁹ Departamento de Física, Centro Universitario de Ciencias Exactase Ingenierias, Universidad de Guadalajara, Guadalajara, Mexico
⁵⁰ Department of Physics, California State University – East Bay, Hayward, CA 94542, USA
⁵¹ Max-Planck Institute for Nuclear Physics, 69117 Heidelberg, Germany
⁵² Universidad Politecnica de Pachuca, Pachuca, Hgo, Mexico
⁵³ Department of Physics, Stevens Institute of Technology, Hoboken, NJ 07030, USA
⁵⁴ Department of Physics, Michigan Technological University, Houghton, MI 49931, USA
⁵⁵ Hubble and Carnegie-Princeton Fellow  
⁵⁶ NASA Marshall Space Flight Center, Astrophysics Office, Huntsville, AL 35812, USA
⁵⁷ Department of Physics and Astronomy, University of Iowa, Van Allen Hall, Iowa City, IA 52242, USA
⁵⁸ Institute of Applied Physics, Irkutsk State University 20, Gagarin Blvd, Irkutsk, 664003, Russia
⁵⁹ Dept. of Physics and Astronomy, University of California, Irvine, CA 92697, USA
⁶⁰ Kislovodsk Solar Station of Main Pulkovo Observatory, PO Box 45, ul. Gagarina 100, Kislovodsk 357700, Russia
⁶¹ Instytut Fizyki Jadrowej im Henryka Niewodniczanskiego Polskiej Akademii Nauk, IFJ-PAN, 31-342 Krakow, Poland
⁶² Dept. of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA
⁶³ University of Leicester, X-ray and Observational Astronomy Research Group, Leicester Institute for Space and Earth Observation, Dept. of Physics & Astronomy, University Road, Leicester, LE1 7RH, UK
⁶⁴ Physics Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
⁶⁵ Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA
⁶⁶ Dept. of Astronomy, University of Wisconsin, Madison, WI 53706, USA
⁶⁷ Dept. of Physics and Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin, Madison, WI 53706, USA
⁶⁸ Institute of Physics, University of Mainz, Staudinger Weg 7, 55099 Mainz, Germany
⁶⁹ Department of Physics, Marquette University, Milwaukee, WI, 53201, USA
⁷⁰ School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA
⁷¹ Université de Mons, 7000 Mons, Belgium
⁷² Physics Department, McGill University, Montreal, QC H3A 2T8, Canada
⁷³ Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mexico
⁷⁴ Lomonosov Moscow State University, Physics Department, Leninskie gory, GSP-1, Moscow 119991, Russia
⁷⁵ Lomonosov Moscow State University, Sternberg Astronomical Institute, Universitetsky Prospekt 13, Moscow 119192, Russia
⁷⁶ Physik-department, Technische Universität München, 85748 Garching, Germany
⁷⁷ Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany
⁷⁸ Bartol Research Institute and Dept. of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
⁷⁹ Dept. of Physics, Yale University, New Haven, CT 06520, USA
⁸⁰ Physics Department, Columbia University, New York, NY 10027, USA
⁸¹ Department of Physics and Astronomy, Barnard College, Columbia University, NY 10027, USA
⁸² Dept. of Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP, UK
⁸³ Universidad Autónoma del Estado de Hidalgo, Pachuca, Mexico
⁸⁴ Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101, USA
⁸⁵ Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA
⁸⁶ Dept. of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA
⁸⁷ Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam-Golm, Germany
⁸⁸ Instituto Nacional de Astrofísica, Óptica y Electrónica, Puebla, Mexico
⁸⁹ Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
⁹⁰ Physics Department, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA
⁹¹ Department of Particle Physics & Astrophysics, Weizmann Institute of Science, Rehovot 7610001, Israel
⁹² Dept. of Physics, University of Wisconsin, River Falls, WI 54022, USA
⁹³ Dept. of Physics and Astronomy, University of Rochester, Rochester, NY 14627, USA
⁹⁴ Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
⁹⁵ Department of Physics, University of California, Santa Barbara, CA 93106-9530, USA
⁹⁶ Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106-4030, USA
⁹⁷ Santa Cruz Institute for Particle Physics and Department of Physics, University of California, SantaCruz, CA 95064, USA
⁹⁸ Nucleo de Astronomia de la Facultad de Ingenieria, Universidad Diego Portales, Av. Ejercito 441, Santiago, Chile
⁹⁹ Millennium Institute of Astrophysics, Santiago, Chile
¹⁰⁰ Department of Physics, Washington University, St. Louis, MO 63130, USA
¹⁰¹ Oskar Klein Centre and Dept. of Physics, Stockholm University, 10691 Stockholm, Sweden
¹⁰² Dept. of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800, USA
¹⁰³ Dept. of Physics, Sungkyunkwan University, Suwon 440-746, Korea
¹⁰⁴ Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany
¹⁰⁵ Instituto de Astrofísica de Canarias, Observatorio del Teide C/via Lactea, s/n, 38205 La Laguna, Tenerife, Spain
¹⁰⁶ Earthquake Research Institute, University of Tokyo, Bunkyo, Tokyo 113-0032, Japan
¹⁰⁷ Dept. of Physics, University of Toronto, Toronto, Ontario M5S 1A7, Canada
¹⁰⁸ Dept. of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487, USA
¹⁰⁹ Dept. of Astronomy and Astrophysics, Pennsylvania State, University, University Park, PA 16802, USA
¹¹⁰ Dept. of Physics, Pennsylvania State University, University Park, PA 16802, USA
¹¹¹ Center for Particle & Gravitational Astrophysics, Institute for Gravitation and the Cosmos, Pennsylvania State University, University Park, PA 16802, USA
¹¹² Center for Theoretical & Observational Cosmology, Institute for Gravitation and the Cosmos, Pennsylvania State University, University Park, PA 16802, USA
¹¹³ Dept. of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
¹¹⁴ Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA
¹¹⁵ Dept. of Physics, University of Wuppertal, 42119 Wuppertal, Germany
¹¹⁶ DESY, 15735 Zeuthen, Germany

^⋆ Corresponding author: N. L. Strotjohann, e-mail: nora.linn.strotjohann@desy.de

Received: 14 February 2017
Accepted: 30 July 2017

Abstract

On February 17, 2016, the IceCube real-time neutrino search identified, for the first time, three muon neutrino candidates arriving within 100 s of one another, consistent with coming from the same point in the sky. Such a triplet is expected once every 13.7 years as a random coincidence of background events. However, considering the lifetime of the follow-up program the probability of detecting at least one triplet from atmospheric background is 32%. Follow-up observatories were notified in order to search for an electromagnetic counterpart. Observations were obtained by Swift’s X-ray telescope, by ASAS-SN, LCO and MASTER at optical wavelengths, and by VERITAS in the very-high-energy gamma-ray regime. Moreover, the Swift BAT serendipitously observed the location 100 s after the first neutrino was detected, and data from the Fermi LAT and HAWC observatory were analyzed. We present details of the neutrino triplet and the follow-up observations. No likely electromagnetic counterpart was detected, and we discuss the implications of these constraints on candidate neutrino sources such as gamma-ray bursts, core-collapse supernovae and active galactic nucleus flares. This study illustrates the potential of and challenges for future follow-up campaigns.