Boschini M J, Torre S Della, Gervasi M, Grandi D, Jóhannesson G, Vacca G La, Masi N, Moskalenko I V, Pensotti S, Porter T A, Quadrani L, Rancoita P G, Rozza D, Tacconi M
INFN, Milano-Bicocca, Milano, Italy.
CINECA, Segrate, Milano, Italy.
Astrophys J. 2018 Feb 20;854(2). doi: 10.3847/1538-4357/aaa75e. Epub 2018 Feb 15.
The local interstellar spectrum (LIS) of cosmic-ray (CR) electrons for the energy range 1 MeV to 1 TeV is derived using the most recent experimental results combined with the state-of-the-art models for CR propagation in the Galaxy and in the heliosphere. Two propagation packages, GALPROP and HelMod, are combined to provide a single framework that is run to reproduce direct measurements of CR species at different modulation levels, and at both polarities of the solar magnetic field. An iterative maximum-likelihood method is developed that uses GALPROP-predicted LIS as input to HelMod, which provides the modulated spectra for specific time periods of the selected experiments for model-data comparison. The optimized HelMod parameters are then used to adjust GALPROP parameters to predict a refined LIS with the procedure repeated subject to a convergence criterion. The parameter optimization uses an extensive data set of proton spectra from 1997 to 2015. The proposed CR electron LIS accommodates both the low-energy interstellar spectra measured by as well as the high-energy observations by PAMELA and AMS-02 that are made deep in the heliosphere; it also accounts for counting rate features measured out of the ecliptic plane. The interstellar and heliospheric propagation parameters derived in this study agree well with our earlier results for CR protons, helium nuclei, and anti-protons propagation and LIS obtained in the same framework.
利用最新的实验结果，结合银河系和日球层中宇宙射线（CR）传播的最先进模型，推导出能量范围为1 MeV至1 TeV的宇宙射线电子的本地星际光谱（LIS）。将两个传播程序包GALPROP和HelMod结合起来，提供一个单一的框架，运行该框架以重现不同调制水平以及太阳磁场两种极性下CR物种的直接测量结果。开发了一种迭代最大似然方法，该方法使用GALPROP预测的LIS作为HelMod的输入，HelMod为所选实验的特定时间段提供调制光谱，用于模型-数据比较。然后使用优化后的HelMod参数来调整GALPROP参数，以预测经过细化的LIS，并根据收敛标准重复该过程。参数优化使用了1997年至2015年质子光谱的大量数据集。所提出的CR电子LIS既包含了[具体仪器名称]测量的低能星际光谱，也包含了日球层深处PAMELA和AMS-02的高能观测结果；它还考虑了在黄道面外测量的计数率特征。本研究中得出的星际和日球层传播参数与我们早期在同一框架下获得的CR质子、氦核和反质子传播及LIS的结果非常吻合。
