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Antiproton Flux in Cosmic Ray Propagation Models with Anisotropic Diffusion
High Energy Astrophysical Phenomena · Submitted 2 Dec 2010
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim A combined fit including in addition the $\bar{p}/p$ data is marginal, suggesting only a partial contribution to the measured antiproton flux.
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The abstract, sentence by sentence
Recently a cosmic ray propagation model has been introduced, where anisotropic diffusion is used as a mechanism to allow for $\mathcal{O}(100)$ km/s galactic winds. This model predicts a reduced antiproton background flux, suggesting an excess is being observed. We implement this model in GALPROP v50.1 and perform a $\chi^2$ analysis for B/C, $^{10}$Be/$^{9}$Be, and the recent PAMELA $\bar{p}/p$ datasets. By introducing a power-index parameter $\alpha$ that dictates the dependence of the diffusion coefficient $D_{xx}$ on height $|z|$ away from the galactic plane, we confirm that isotropic diffusion models with $\alpha=0$ cannot accommodate high velocity convective winds suggested by ROSAT, while models with $\alpha=1$ ($D_{xx}\propto |z|$) can give a very good fit. A fit to B/C and $^{10}$Be/$^{9}$Be data predicts a lower $\bar{p}/p$ flux ratio than the PAMELA measurement at energies between approximately 2 GeV to 20 GeV. A combined fit including in addition the $\bar{p}/p$ data is marginal, suggesting only a partial contribution to the measured antiproton flux.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | Recently a cosmic ray propagation model has been introduced, where anisotropic diffusion is used as a mechanism to allow for $\mathcal{O}(100)$ km/s galactic winds. | background 1.00 | 0.06 | 0.03 | asserted 0.99 |
| s1 | This model predicts a reduced antiproton background flux, suggesting an excess is being observed. | background 0.74 | 0.09 | 0.17 | hedged possibility 0.94 |
| s2 | We implement this model in GALPROP v50.1 and perform a $\chi^2$ analysis for B/C, $^{10}$Be/$^{9}$Be, and the recent PAMELA $\bar{p}/p$ datasets. | method 0.93 | 0.95 | 0.05 | asserted 0.97 |
| s3 | By introducing a power-index parameter $\alpha$ that dictates the dependence of the diffusion coefficient $D_{xx}$ on height $|z|$ away from the galactic plane, we confirm that isotropic diffusion models with $\alpha=0$ cannot accommodate high velocity convective winds suggested by ROSAT, while models with $\alpha=1$ ($D_{xx}\propto |z|$) can give a very good fit. | result 0.83 | 0.93 | 0.34 | asserted 0.99 |
| s4 | A fit to B/C and $^{10}$Be/$^{9}$Be data predicts a lower $\bar{p}/p$ flux ratio than the PAMELA measurement at energies between approximately 2 GeV to 20 GeV. | result 1.00 | 0.90 | 0.30 | asserted 0.99 |
| s5 | A combined fit including in addition the $\bar{p}/p$ data is marginal, suggesting only a partial contribution to the measured antiproton flux. | interpretation 0.62 | 0.92 | 0.45 | hedged possibility 0.98 |
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The paper
Original abstract
Recently a cosmic ray propagation model has been introduced, where anisotropic diffusion is used as a mechanism to allow for $\mathcal{O}(100)$ km/s galactic winds. This model predicts a reduced antiproton background flux, suggesting an excess is being observed. We implement this model in GALPROP v50.1 and perform a $\chi^2$ analysis for B/C, $^{10}$Be/$^{9}$Be, and the recent PAMELA $\bar{p}/p$ datasets. By introducing a power-index parameter $\alpha$ that dictates the dependence of the diffusion coefficient $D_{xx}$ on height $|z|$ away from the galactic plane, we confirm that isotropic diffusion models with $\alpha=0$ cannot accommodate high velocity convective winds suggested by ROSAT, while models with $\alpha=1$ ($D_{xx}\propto |z|$) can give a very good fit. A fit to B/C and $^{10}$Be/$^{9}$Be data predicts a lower $\bar{p}/p$ flux ratio than the PAMELA measurement at energies between approximately 2 GeV to 20 GeV. A combined fit including in addition the $\bar{p}/p$ data is marginal, suggesting only a partial contribution to the measured antiproton flux.
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References
How the literature uses it
2 arXiv papers cite this in 2 sentences
What it cites · 17 sentences without a confident label
Uses the method or tool of 2 papers
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In this paper we implement the anisotropic propagation model of [ref] in the public CR propagation code GALPROP v50.1 [ref] , and explore varying levels of diffusion anisotropy by adjusting the rate at which the diffusion intensity increases with distance from the galactic plane.
An Anisotropic Propagation Model for Galactic Cosmic Rays · Introduction · 0.88
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In this paper we implement the anisotropic propagation model of [ref] in the public CR propagation code GALPROP v50.1 [ref] , and explore varying levels of diffusion anisotropy by adjusting the rate at which the diffusion intensity increases with distance from the galactic plane.
The GALPROP Cosmic-Ray Propagation Code · Introduction · 0.88
Uses data or values from 3 papers
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For $p̅/p$: PAMELA 2010 [ref] .
PAMELA results on the cosmic-ray antiproton flux from 60 MeV to 180 GeV in kinetic energy · Analysis · 1.00
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For B/C: HEAO-3 [ref] , CREAM [ref] , ACE [ref] , and ATIC-2 [ref] .
Relative abundances of cosmic ray nuclei B-C-N-O in the energy region from 10 GeV/n to 300 GeV/n. Results from ATIC-2 (the science flight of ATIC) · Analysis · 0.99
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Except for the PAMELA $p̅/p$ measurements, all the data are obtained from the Galactic Cosmic Ray Database [ref] .
A Galactic Cosmic-Ray Database · Analysis · 0.95
Compares with 4 papers
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The coefficients resulting from the inclusion of spatially dependent diffusion and convection have been computed and they agree to those in [ref] in the limit of an equidistant computational grid.
An Anisotropic Propagation Model for Galactic Cosmic Rays · GALPROP Modifications · 0.95
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These values are somewhat high compared to $v_A≃30$ km/s obtained for models with no convective wind [ref] , and $v_A≃20$ km/s expected for the warm ionized phase of the interstellar medium [ref] .
Propagation of cosmic-ray nucleons in the Galaxy · Combined fit to B/C and $^10$Be/$^9$Be · 0.98
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These values are consistent with previous studies involving GALPROP [ref] (see also [ref] ) and also with magneto-hydrodynamic theory, which predicts $δ=1/3$ for Kolmogorov-type turbulence power spectrum, and $δ=1/2$ for a Kraichnan-type spectrum.
Uncertainties of Cosmic Ray Spectra and Detectability of Antiproton mSUGRA Contributions With PAMELA · Combined fit to B/C and $^10$Be/$^9$Be · 0.87
Cites as background 12 papers
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These include both semi-analytic [ref] as well as fully numerical treatments [ref] .
Cosmic-Ray Nuclei, Antiprotons and Gamma-rays in the Galaxy: a New Diffusion Model · Introduction · 0.85
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These include both semi-analytic [ref] as well as fully numerical treatments [ref] .
The GALPROP Cosmic-Ray Propagation Code · Introduction · 0.85
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These include both semi-analytic [ref] as well as fully numerical treatments [ref] .
Unified interpretation of cosmic-ray nuclei and antiproton recent measurements · Introduction · 0.85
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