Journal Article

An absence of neutrinos associated with cosmic-ray acceleration in γ-ray bursts

Christy, B, Baker, M, Becker, K-H, Bechet, S, Altmann, D, Bay, R, Bell, M, Blaufuss, E, Benabderrahmane, M L, Clevermann, F, Chirkin, D, Abdou, Y, Caballero-Mora, K S, Bai, X, Casier, M, Bissok, M, Bazo Alba, JL, Brown, A M, Barwick, S W, Ahlers, M, Beatty, J J, Cowen, D F, Bose, D, Abu-Zayyad, T, Bertrand, D, Bindig, D, Ackermann, M, Cohen, S, Buitink, S, Abbasi, R, Auffenberg, J, Berley, D, Boser, S, Bernardini, E, Becker, J K, Blumenthal, J, Botner, O, et. al, Beattie, K, Colnard, C, Adams, J, Aguilar, JA, Andeen, K, Bohm, C, BenZvi, S, Besson, D Z, Boersma, D J, Brayeur, L, Carson, M, Berdermann, J, Berghaus, P

2012

Overview

An upper limit has been placed on the flux of energetic neutrinos associated with γ-ray bursts that is at least a factor of 3.7 below the predictions, implying either that γ-ray bursts are not the only sources of high-energy cosmic rays or that the efficiency of neutrino production is much lower than has been predicted. IceCube pours cold water on current theory The IceCube particle detector at the South Pole is designed to detect neutrinos from high-energy astronomical events. Here, the IceCube Collaboration presents the results of a search for high-energy (teraelectronvolt; 10 12 -electronvolt) neutrinos from γ-ray bursts (GRBs). The team finds an upper limit on the flux of energetic neutrinos associated with GRBs that is at least a factor of 3.7 below the predictions. This implies that either GRBs are not the only sources of cosmic rays with energies greater than 10 18 electronvolts, or the efficiency of neutrino production is much lower than has been predicted. Either way, our current theories of cosmic-ray and neutrino production in GRBs will need to be revisited. Very energetic astrophysical events are required to accelerate cosmic rays to above 10 18  electronvolts. GRBs (γ-ray bursts) have been proposed as possible candidate sources 1 , 2 , 3 . In the GRB ‘fireball’ model, cosmic-ray acceleration should be accompanied by neutrinos produced in the decay of charged pions created in interactions between the high-energy cosmic-ray protons and γ-rays 4 . Previous searches for such neutrinos found none, but the constraints were weak because the sensitivity was at best approximately equal to the predicted flux 5 , 6 , 7 . Here we report an upper limit on the flux of energetic neutrinos associated with GRBs that is at least a factor of 3.7 below the predictions 4 , 8 , 9 , 10 . This implies either that GRBs are not the only sources of cosmic rays with energies exceeding 10 18  electronvolts or that the efficiency of neutrino production is much lower than has been predicted.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 639/766/33/34 / Acceleration / Astronomy / Bursts / Cosmic rays / Decay / Earth, ocean, space / Elementary particle and nuclear processes / Exact sciences and technology / Fireballs / Flux / Fundamental aspects of astrophysics / Fundamental astronomy and astrophysics. Instrumentation, techniques, and astronomical observations / Gamma-ray sources ; gamma-ray bursts / Humanities and Social Sciences / letter / Mathematical models / multidisciplinary / Neutrinos / Science / Science (multidisciplinary) / Stellar systems. Galactic and extragalactic objects and systems. The universe / Unidentified sources and radiation outside the solar system