BAYESIAN ANALYSIS OF COSMIC RAY PROPAGATION: EVIDENCE AGAINST HOMOGENEOUS DIFFUSION

2016/02/29 by G. Jóhannesson, R. Ruiz de Austri, Aaron C. Vincent +11 · 171 citations
Physics and Astronomy · #Algorithm #Artificial intelligence #Artificial neural network #Astrophysics #Astrophysics and Cosmic Phenomena #Backpropagation #Bar (unit) #Bayesian probability #Computational physics #Computer science #Cosmic ray #Dark Matter and Cosmic Phenomena #Diffusion #Particle Detector Development and Performance #Physics #Propagation of uncertainty #astro-ph.GA #astro-ph.HE

paper · pdf · doi:10.3847/0004-637x/824/1/16

published in The Astrophysical Journal 824(1), 16 (IOP Publishing) · 20 pages, 10 figures, 5 tables. v2 accepted for publication in ApJ

arxiv created 2016/04/12 · openalex publication_date 2016/06/03 · arxiv updated 2016/06/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

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 , , and He) from the usual light elements (Be, B, C, N, and O). We find that the propagation parameters that best-fit , and He data are significantly different from those that fit light elements, including the B/C and 10 Be/ 9 Be 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.

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