G. Jóhannesson
Bayesian analysis of cosmic-ray propagation: evidence against homogeneous diffusion
Jóhannesson, G.; Ruiz de Austri, R.; Vincent, A.C.; Moskalenko, I.V.; Orlando, E.; Porter, T.A.; Strong, A.W.; Trotta, R.; Feroz, F.; Graff, P.; Hobson, M.P.
Authors
R. Ruiz de Austri
A.C. Vincent
I.V. Moskalenko
E. Orlando
T.A. Porter
A.W. Strong
R. Trotta
F. Feroz
P. Graff
M.P. Hobson
Abstract
We present the results of the most complete scan of the parameter space for cosmic ray (CR) injection and propagation. We perform a Bayesian search of the main GALPROP parameters, using the MultiNest nested sampling algorithm, augmented by the BAMBI neural network machine-learning package. This is the first study to separate out low-mass isotopes (p, $\bar{p}$, and He) from the usual light elements (Be, B, C, N, and O). We find that the propagation parameters that best-fit $p,\bar{p}$, and He data are significantly different from those that fit light elements, including the B/C and 10Be/9Be secondary-to-primary ratios normally used to calibrate propagation parameters. This suggests that each set of species is probing a very different interstellar medium, and that the standard approach of calibrating propagation parameters using B/C can lead to incorrect results. We present posterior distributions and best-fit parameters for propagation of both sets of nuclei, as well as for the injection abundances of elements from H to Si. The input GALDEF files with these new parameters will be included in an upcoming public GALPROP update
Citation
Jóhannesson, G., Ruiz de Austri, R., Vincent, A., Moskalenko, I., Orlando, E., Porter, T., …Hobson, M. (2016). Bayesian analysis of cosmic-ray propagation: evidence against homogeneous diffusion. Astrophysical Journal, 824(1), Article 16. https://doi.org/10.3847/0004-637x/824/1/16
Journal Article Type | Article |
---|---|
Acceptance Date | Mar 29, 2016 |
Online Publication Date | Jun 3, 2016 |
Publication Date | Jun 3, 2016 |
Deposit Date | Aug 19, 2016 |
Publicly Available Date | Aug 22, 2016 |
Journal | Astrophysical Journal |
Print ISSN | 0004-637X |
Electronic ISSN | 1538-4357 |
Publisher | American Astronomical Society |
Peer Reviewed | Peer Reviewed |
Volume | 824 |
Issue | 1 |
Article Number | 16 |
DOI | https://doi.org/10.3847/0004-637x/824/1/16 |
Publisher URL | http://iopscience.iop.org/article/10.3847/0004-637X/824/1/16/meta |
Related Public URLs | https://arxiv.org/abs/1602.02243 |
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Copyright Statement
© 2016. The American Astronomical Society. All rights reserved.
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