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首页> 外文会议>Proceedings of the 32nd International Cosmic Ray Conference >Cosmic-ray helium hardening
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Cosmic-ray helium hardening

机译：宇宙射线氦硬化

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Recent observations by the ATIC-2, CREAM and PAMELA experiments suggest that the spectrum of cosmic-ray(CR) helium is harder than that of CR protons below the knee energy and all CR spectra become hard at 100GeVucleon. According to DSA theory, the spectrum of accelerated particles at a shock does not depend on CR el-ements,but depends only on the velocity profile of the shock. Thus, naively, recent CR observations seem to show thatthe acceleration site of CR helium is different from that of CR protons. We propose a new idea, that higher energy CRsare generated in a more helium-rich region, to explain the hardening without introducing different sources for CR helium.We argue that CRs are produced in a chemically enriched region, such as a superbubble, and the outward-decreasingabundance naturally leads to the hard spectrum of CR helium if CRs escape from the supernova remnant shock in anenergy-dependent way. Our idea uses the fact that CRs escaping from SNRs generally have a different spectrum thanthose of the acceleration site. The runaway CR spectrum depends not only on the acceleration spectrum at shocks but alsoon the evolution of the maximum energy and the number of accelerated CRs. We also suggest that the spectral hardeningof CRs is caused by the decreasing Mach number in the high-temperature medium. Both the inhomogeneous abundanceand the high temperature can be realized in the hot superbubbles with multiple supernovae.
机译：ATIC-2，CREAM和PAMELA实验最近的观察表明，宇宙射线（CR）氦的光谱比拐点能量以下的CR质子的光谱更硬，并且所有CR光谱在100GeV /核子时都变硬。根据DSA理论，冲击时加速粒子的频谱不取决于CR元素，而仅取决于冲击的速度曲线。因此，天真的，最近的CR观察似乎表明CR氦的加速部位与CR质子的加速部位不同。我们提出了一个新的想法，即在一个更富氦的区域中产生更高能的CRs，以解释这种硬化过程而没有引入不同来源的CR氦。我们认为CR发生在一个化学富集的区域（例如超级气泡）中，并且如果CR以无能依赖的方式从超新星残余冲击中逸出，则向外递减的丰度自然会导致CR氦的硬光谱。我们的想法利用了这样一个事实，即从SNR逃逸的CR通常具有与加速站点不同的频谱。失控的CR谱不仅取决于冲击时的加速度谱，还取决于最大能量的演化和加速的CR数。我们还建议，CRs的光谱硬化是由高温介质中马赫数的减少引起的。在具有多个超新星的热超气泡中都可以实现不均匀丰度和高温。

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