Abundances of Co-59 and Ni-59 in the cosmic ray flux

作者：Neronov A^*; Meynet G

来源：Astronomy & Astrophysics, 2016, 588: A86.

DOI：10.1051/0004-6361/201527762

• nuclear reactions
• nucleosynthesis, abundances
• stars: massive
• supernovae: general
• acceleration of particles
• cosmic rays

Context. Two main hypotheses for the origin of Galactic cosmic rays are the supernova and superbubble origin hypotheses.
Aims. We analyse the evidence for the superbubble hypothesis provided by the measurements of the relativive abundances of isotopes of cobalt and nickel in the cosmic ray flux.
Methods. We compare the measured upper limit on the abundance of Ni-59 in the cosmic ray flux with the Ni-59 abundance predictions of the most recent stellar evolution models. Non-detection of Ni-59 in the cosmic ray flux has previously been attributed to a long time delay of the order of 10(5) yr between the moment of supernova explosion and the onset of particle acceleration process. This long time delay was considered as an argument in favour of the superbubble scenario.
Results. We show that the recent calculation of the Ni-59 yield of massive stars, which takes the initial mass range up to 120 solar masses into account and includes stellar rotation, results in prediction of low Ni-59 abundance relative to its decay product Co-59. The predicted abundance is consistent with the upper bound on Ni-59 abundance in the cosmic ray flux for the supernova parameters assumed. This result removes the necessity of decay of Ni-59 in the time interval between the supernova explosion and the onset of acceleration process and restores the consistency of measurements of Ni-59/Co-59 abundances with the "supernova" hypothesis of the CR origin.

• 出版日期2016-4