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arXiv 1405.2835astro-ph.HE
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TeV cosmic-ray在无数模型II中的质子和氦谱

TeV cosmic-ray proton and helium spectra in the myriad model II

Wei Liu, Pierre Salati, Xuelei Chen

摘要:

最近的观测表明,宇宙射线核谱在100 GeV以上开始硬化,这与传统的稳态宇宙射线模型相矛盾。我们认为这种异常是由于本地年轻宇宙线源释放的宇宙射线的传播效应造成的,宇宙线总通量的计算应采用将本地星表源的贡献加到本底的万有模型。然而,虽然在这个模型中可以优雅地解释硬化,但从拟合中获得的模型参数偏向于银河系中具有快速扩散和低超新星速率的区域,与其他观测结果相矛盾。在本文中,我们进一步探讨了这一模型,以建立一个协调的图片。已经考虑了与宇宙射线源有关的两种可能的改进。首先,我们考虑了一种螺旋源分布模型,而不是通常的轴对称圆盘模型。其次,对于对于硬化至关重要的附近和年轻的源,我们允许依赖于能量的逃逸时间。我们发现,主要的改进来自能量依赖的逃逸时间的本地源,并与这两个修改,不仅宇宙线质子和氦异常的解决,而且参数达到合理的范围值与其他分析兼容。

英文摘要:

Recent observations show that the cosmic ray nuclei spectra start to harden above 100 GeV, in contradiction with the conventional steady-state cosmic ray model. We had suggested that this anomaly is due to the propagation effect of cosmic rays released from local young cosmic ray sources, the total flux of the cosmic ray should be computed with the myriad model, where contribution from sources in local catalog is added to the background. However, while the hardening could be elegantly explained in this model, the model parameters obtained from the fit skew toward a region with fast diffusion and low supernova rate in the Galaxy, in tension with other observations. In this paper, we further explore this model in order to set up a concordant picture. Two possible improvements related to the cosmic ray sources have been considered. Firstly, instead of the usual axisymmetric disk model, we considered a spiral model of source distribution. Secondly, for the nearby and young sources which are paramount to the hardening, we allow for an energy-dependent escape time. We find that major improvement comes from the energy-dependent escape time of the local sources, and with both modifications, not only the cosmic ray proton and helium anomalies are solved, but also the parameters attain reasonable range values compatible with other analysis.

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