Blasi Pasquale
INAF/Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi, 5 50125 Firenze, Italy.
Phys Rev Lett. 2009 Jul 31;103(5):051104. doi: 10.1103/PhysRevLett.103.051104.
We show that the positron excess measured by the PAMELA experiment in the region between 10 and 100 GeV may well be a natural consequence of the standard scenario for the origin of Galactic cosmic rays. The "excess" arises because of positrons created as secondary products of hadronic interactions inside the sources, but the crucial physical ingredient which leads to a natural explanation of the positron flux is the fact that the secondary production takes place in the same region where cosmic rays are being accelerated. Therefore secondary positrons (and electrons) participate in the acceleration process and turn out to have a very flat spectrum, which is responsible, after propagation in the Galaxy, for the observed positron excess. This effect cannot be avoided though its strength depends on the values of the environmental parameters during the late stages of evolution of supernova remnants.
我们表明，帕梅拉实验在10至100 GeV能量区间测量到的正电子过量很可能是银河系宇宙射线起源的标准情景的自然结果。“过量”是由于源内部强子相互作用产生的次级产物正电子所致，但导致对正电子通量进行自然解释的关键物理因素是次级产生发生在宇宙射线被加速的同一区域这一事实。因此，次级正电子（和电子）参与加速过程，结果具有非常平缓的能谱，在银河系中传播后，这一能谱导致了观测到的正电子过量。尽管这种效应的强度取决于超新星遗迹演化后期环境参数的值，但这种效应无法避免。
