Production and Propagation of Cosmic-Ray Positrons and Electrons
Production and Propagation of Cosmic-Ray Positrons and Electrons
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DOI：
10.1086/305152
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发表时间：
1997-10
期刊：
影响因子：
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通讯作者：
I. Moskalenko;A. Strong
中科院分区：
文献类型：
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作者：
I. Moskalenko;A. Strong
本文利用银河系宇宙线传播的扩散晕模型，对宇宙线次级正电子能谱进行了新的计算。该代码自洽地计算初级和次级核子，初级电子，次级正电子和电子的光谱。首先调整模型，使之与观测到的宇宙射线硼/碳比一致，然后计算星际质子和氦的光谱;这些光谱用于获得最终以相同模型参数传播的次级正电子/电子的源函数。再次使用相同的模型来评估初级电子谱。碎片和能量损失计算使用现实的星际气体和辐射场的分布，扩散再加速也被纳入。我们的研究包括对正电子次级衰变计算的重新评估。预测的正电子分数是在良好的协议与测量高达10 GeV，超过所观察到的通量高于计算。由于正电子分数现在在1-10 GeV的范围内精确测量，我们的初级电子谱应该是在这个范围内的真正星际光谱的一个很好的估计，对伽马射线和太阳调制研究的兴趣。我们进一步表明，一个更硬的星际核子谱，类似于建议解释EGRET弥漫银河伽玛射线观测超过1 GeV，可以重现10 GeV以上的正电子观测，而不需要一个主要的正电子组件。
We have made a new calculation of the cosmic-ray secondary positron spectrum using a diffusive halo model for Galactic cosmic-ray propagation. The code computes self-consistently the spectra of primary and secondary nucleons, primary electrons, and secondary positrons and electrons. The models are first adjusted to agree with the observed cosmic-ray boron/carbon ratio, and the interstellar proton and helium spectra are then computed; these spectra are used to obtain the source function for the secondary positrons/electrons that are finally propagated with the same model parameters. The primary electron spectrum is evaluated, again using the same model. Fragmentation and energy losses are computed using realistic distributions for the interstellar gas and radiation fields, and diffusive reacceleration is also incorporated. Our study includes a critical reevaluation of the secondary decay calculation for positrons. The predicted positron fraction is in good agreement with the measurements up to 10 GeV, beyond which the observed flux is higher than that calculated. Since the positron fraction is now measured accurately in the 1-10 GeV range, our primary electron spectrum should be a good estimate of the true interstellar spectrum in this range, of interest for gamma-ray and solar modulation studies. We further show that a harder interstellar nucleon spectrum, similar to that suggested to explain EGRET diffuse Galactic gamma-ray observations above 1 GeV, can reproduce the positron observations above 10 GeV without requiring a primary positron component.