arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1012.0587astro-ph.HEhep-ph
收藏

具有各向异性扩散的Cosmic Ray传输模型中的反质子通量

Antiproton Flux in Cosmic Ray Propagation Models with Anisotropic Diffusion

Phillip Grajek, Kaoru Hagiwara

摘要:

最近一个宇宙射线传播模型已经被引入,其中各向异性扩散被用作允许$\mathcal{O}(100)$ km/s星系风的机制。这个模型预测了一个减少的反质子背景通量,这表明正在观察过量。我们在GALPROP v50.1中实现了这个模型,并对B/C、$^{10}$ Be/ $^{9}$ Be和最近的PAMELA $\bar{p}/p$数据集进行了$χ^2$分析。通过引入一个幂指数参数$α$,决定了高度$|z|$远离银道面的扩散系数$D_{xx}$的依赖关系,我们确认,各向同性扩散模型与$α=0$不能容纳高速对流风建议ROSAT,而模型与$α=1$($D_{xx}\propto |z|$)可以得到一个很好的拟合。B/C和$^{10}$ Be/ $^{9}$ Be数据的拟合预测,在大约2 GeV至20 GeV之间的能量下,$\bar{p}/p$ $\bar{p}/p$的通量比低于PAMELA测量值。一个组合的拟合,包括另外的$\bar{p}/p$数据是边际的,这表明只有部分的测量反质子通量的贡献。

英文摘要:

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 $χ^2$ analysis for B/C, $^{10}$Be/$^{9}$Be, and the recent PAMELA $\bar{p}/p$ datasets. By introducing a power-index parameter $α$ 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 $α=0$ cannot accommodate high velocity convective winds suggested by ROSAT, while models with $α=1$ ($D_{xx}\propto |z|$) 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.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑