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

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Bibliographic Details
Title:	An absence of neutrinos associated with cosmic-ray acceleration in ?-ray bursts.
Authors:	Abbasi, R., Abdou, Y., Abu-Zayyad, T., Ackermann, M., Adams, J., Aguilar, J. A., Ahlers, M., Altmann, D., Andeen, K., Auffenberg, J., Bai, X., Baker, M., Barwick, S. W., Bay, R., Bazo Alba, J. L., Beattie, K., Beatty, J. J., Bechet, S., Becker, J. K., Becker, K.-H.
Source:	Nature. 4/19/2012, Vol. 484 Issue 7394, p351-354. 4p. 4 Graphs.
Subjects:	Neutrinos, Cosmic rays, Astrophysics, Meteors, Pions, Protons
Abstract:	Very energetic astrophysical events are required to accelerate cosmic rays to above 1018?electronvolts. GRBs (?-ray bursts) have been proposed as possible candidate sources. 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 ?-rays. Previous searches for such neutrinos found none, but the constraints were weak because the sensitivity was at best approximately equal to the predicted flux. 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. This implies either that GRBs are not the only sources of cosmic rays with energies exceeding 1018?electronvolts or that the efficiency of neutrino production is much lower than has been predicted. [ABSTRACT FROM AUTHOR]
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Database:	Psychology and Behavioral Sciences Collection

Description
Abstract:	Very energetic astrophysical events are required to accelerate cosmic rays to above 1018?electronvolts. GRBs (?-ray bursts) have been proposed as possible candidate sources. 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 ?-rays. Previous searches for such neutrinos found none, but the constraints were weak because the sensitivity was at best approximately equal to the predicted flux. 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. This implies either that GRBs are not the only sources of cosmic rays with energies exceeding 1018?electronvolts or that the efficiency of neutrino production is much lower than has been predicted. [ABSTRACT FROM AUTHOR]
ISSN:	00280836
DOI:	10.1038/nature11068