The last Gamma Ray Burst in our Galaxy? On the observed cosmic ray excess at particle energy 1018 eV

Peter L. Biermann, Gustavo Medina Tanco, Ralph Engel, Giovanna Pugliese

Paper: ApJLetters, Jan 2004, in press

EPrint Server: astro-ph/0401150


Abstract:

Here we propose that the excess flux of particle events of energy near 1018 eV from the direction of the Galactic Center region is due to the production of cosmic rays by the last few Gamma Ray Bursts in our Galaxy. The basic idea is that protons get accelerated inside Gamma Ray Bursts, then get ejected as neutrons, decay and so turn back into protons, meander around the inner Galaxy for some time, and then interact again, turning back to neutrons to be observed at our distance from the Galactic Center region, where most star formation is happening in our Galaxy. We demonstrate that this suggestion leads to a successful interpretation of the data, within the uncertainties of cosmic ray transport time scales in the inner Galaxy, and in conjunction with many arguments in the literature.


Preprints available from the authors at gustavo@astro.iag.usp.br , or the raw TeX (no figures) if you click here.

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