Unified interpretation of cosmic-ray nuclei and antiproton recent measurements

TL;DR

This study uses the DRAGON code to analyze recent cosmic ray data, constraining propagation parameters and favoring Kraichnan diffusion, with implications for understanding cosmic ray origins and potential exotic sources.

Contribution

It provides a unified analysis of cosmic ray nuclei and antiproton data, constraining propagation parameters within a diffusion-reacceleration model for the first time.

Findings

Allowed diffusion coefficient spectral index range: 0.3 to 0.6.

Kraichnan diffusion is favored over Kolmogorov.

Limited reacceleration velocity range (10-20 km/s) is consistent with data.

Abstract

We use our numerical code, DRAGON, to study the implications of recent data on our knowledge of the propagation properties of cosmic ray nuclei in the Galaxy. We show that B/C (as well as N/O and C/O) data, including those recently taken by CREAM, and ${\bar p}/p$ data, especially including recent PAMELA results, can consistently be fitted within a unique diffusion-reacceleration model. The requirement that light nuclei and $\bar p$ data are consistently reproduced within experimental uncertainties places significant limits on the main propagation parameters. In particular, we find the allowed range of the diffusion coefficient spectral index to be $0.3 < \delta < 0.6$ at 95% confidence level and that Kraichnan type diffusion is favored with respect to Kolmogorov. While some amount of reacceleration is required, only a limited range of the Alfv\'en velocity value ($10 \simleq v_A \simleq 20 \km \s^{-1}$) is allowed by a combined analysis of nuclear and antiproton data, which we perform here for the first time. If antiproton data are not used to constrain the propagation parameters, a larger set of models is allowed. In this case, we determine which combinations of the relevant parameters maximize and minimize the antiproton flux under the condition of still fitting light nuclei data at 95% C.L. These models may then be used to constrain a possible extra antiproton component arising from astrophysical or exotic sources (e.g. dark matter annihilation or decay).