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首页> 外文期刊>The Astrophysical journal >HELIOSPHERIC MODULATION OF COSMIC-RAY POSITRONS AND ELECTRONS: EFFECTS OF THE HELIOSHEATH AND THE SOLAR WIND TERMINATION SHOCK
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HELIOSPHERIC MODULATION OF COSMIC-RAY POSITRONS AND ELECTRONS: EFFECTS OF THE HELIOSHEATH AND THE SOLAR WIND TERMINATION SHOCK

机译：宇宙射线正电子和电子的日球调制：太阳鞘和太阳风终止激波的影响

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摘要

The importance of the solar wind termination shock (TS) and the modulation that may occur in the heliosheath have become most relevant, as emphasized by cosmic-ray observations of the Voyager spacecraft in the distant heliosphere close to the TS. The role of the TS and that of the heliosheath on cosmic-ray electrons and positrons are studied with a numerical model, including global drifts and a Jovian electron source. The consequent charge-sign dependence is computed using improved local interstellar spectra and new fundamentally derived diffusion coefficients. The importance of modulation in the heliosheath is studied for the two species, as well as the differences between a model with and one without a TS. We found that the modulation in the heliosheath depends on the particle species, is strongly dependent on the energy of the cosmic rays and the magnetic polarity cycle, and is enhanced by the inclusion of the TS. From the computations it is possible to estimate the ratio of modulation occurring in the heliosheath to the total modulation between the heliopause and Earth. For electrons the factor modulation in the heliosheath becomes comparable to the factor between the TS and Earth at low energies for both polarity epochs. During A > 0 cycles the heliosheath cannot really be considered a modulation "barrier" above ～150 MeV for electrons, while for positrons this occurs at somewhat higher energies during the A < 0 cycle. The presence of the TS is thus more pronounced for electron modulation during A > 0 polarity cycles but for positron modulation during A < 0 cycles. For positrons, with a completely differently shaped local interstellar spectrum, the modulated spectra have a very mild energy dependence below ～300 MeV, even at Earth, in contrast to electrons, protons, and antiprotons. These characteristic spectral features may be helpful for distinguishing between electron and positron spectra when measured near and at Earth. These simulations can be of use for future missions to the outer heliosphere and beyond.
机译：太阳风终止冲击（TS）的重要性和日射鞘中可能发生的调制已变得最相关，正如在靠近TS的遥远太阳圈中对旅行者号飞船的宇宙射线观测所强调的那样。用数值模型研究了TS和太阳鞘在宇宙射线电子和正电子上​​的作用，包括整体漂移和木星电子源。随之而来的电荷符号依赖性是使用改进的局部星际光谱和新的基本推导的扩散系数来计算的。研究了两种物种在鞘管中调制的重要性，以及带有和不带有TS的模型之间的差异。我们发现，日鞘中的调制取决于粒子种类，强烈依赖于宇宙射线的能量和磁极性循环，并且通过包含TS得以增强。从计算中可以估计出日鞘中发生的调制与绝经与地球之间总调制的比率。对于电子来说，对于两个极性历元来说，日鞘中的因子调制变得可以与低能下TS和地球之间的因子进行比较。在A> 0周期内，电子束鞘实际上不能被认为是电子在〜150 MeV以上的调制“势垒”，而对于正电子，在A <0周期内，它以较高的能量发生。因此，TS的存在对于A> 0极性周期内的电子调制更为明显，而对于A <0周期周期内的正电子调制更为明显。对于正电子，具有完全不同形状的局部星际光谱，与电子，质子和反质子相比，即使在地球上，即使在地球上，调制后的光谱对能量的依赖性也很弱，低于〜300 MeV。当在地球附近和地球上测量时，这些特征光谱特征可能有助于区分电子光谱和正电子光谱。这些模拟可用于将来向外太阳圈及其他区域的飞行任务。

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