Cosmic ray protons and electrons from supernova remnants
Cosmic ray protons and electrons from supernova remnants
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来自超新星遗迹的宇宙射线质子和电子
DOI：
10.1051/0004-6361/202140448
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发表时间：
2021
影响因子：
6.5
通讯作者：
Caprioli, D.
中科院分区：
文献类型：
--
作者：
Cristofari, P.;Blasi, P.;Caprioli, D.
超新星遗迹在整个演化过程中释放的宇宙射线质子和电子的光谱人们知之甚少，因为很难解释激波前沿下游的粒子逃逸和限制，那里同时存在绝热和辐射损失。由于电子主要通过同步加速器损失来损失能量，因此很自然地要问释放到星际介质中的光谱是否可能与强子对应物的光谱不同。对穿过银河系的宇宙射线传输的独立研究要求电子和质子的源光谱有很大不同。因此，上述问题具有现象学相关性。 目的在这里，我们计算不同类型超新星演化过程中释放的宇宙射线质子的光谱，解释了上游区域的逃逸以及激波下游平流传播并随后释放的粒子的绝热损失。对电子进行了相同的计算，除了绝热损失之外，我们还考虑了冲击后遭受的辐射损失。这些电它们随时间的演化是通过数值求解描述电子和质子的绝热和辐射损失的平流方程而得出的。还考虑了不断逃离超新星遗迹的粒子的通量。结果通过对由于非共振和共振流不稳定性及其饱和而导致的磁场放大进行分析处理，计算了震后区域的磁场。将所得磁场与有关磁场强度对冲击速度的依赖性的可用观测结果集进行比较。我们发现，当场仅是宇宙射线驱动的非共振不稳定性增长的结果时，超新星遗迹释放的电子和质子的光谱确实不同；然而，这种差异只有在能量≳100−1000 GeV时才变得明显，而电子能谱的观测要求这种差异在低至∼10 GeV的能量下才存在。如此低能量的效应需要在超新星遗迹演化的后期阶段进行大量的磁场放大（冲击速度<1000 km s−1）；这可能不是由于流动不稳定，而是由于流体动力学过程。我们评论了这种条件的可行性，并推测电子和质子之间光谱形状的差异可能反映了一些未知的加速效应或源周围茧中的额外能量损失。
ContextThe spectrum of cosmic ray protons and electrons released by supernova remnants throughout their evolution is poorly known because of the difficulty in accounting for particle escape and confinement downstream of a shock front, where both adiabatic and radiative losses are present. Since electrons lose energy mainly through synchrotron losses, it is natural to ask whether the spectrum released into the interstellar medium may be different from that of their hadronic counterpart. Independent studies of cosmic ray transport through the Galaxy require that the source spectrum of electrons and protons be very different. Therefore, the above question acquires a phenomenological relevance.AimsHere we calculate the spectrum of cosmic ray protons released during the evolution of supernovae of different types, accounting for the escape from the upstream region and for adiabatic losses of particles advected downstream of the shock and liberated at later times. The same calculation is carried out for electrons, where in addition to adiabatic losses we take the radiative losses suffered behind the shock into account. These electrons are dominated by synchrotron losses in the magnetic field, which most likely is self-generated by cosmic rays accelerated at the shock.MethodsWe use standard temporal evolution relations for supernova shocks expanding in different types of interstellar media together with an analytic description of particle acceleration and magnetic field amplification to determine the density and spectrum of cosmic ray particles. Their evolution in time is derived by numerically solving the equation describing advection with adiabatic and radiative losses for electrons and protons. The flux from particles continuously escaping the supernova remnants is also accounted for.ResultsThe magnetic field in the post-shock region is calculated by using an analytic treatment of the magnetic field amplification due to nonresonant and resonant streaming instability and their saturation. The resulting field is compared with the available set of observational results concerning the dependence of the magnetic field strength upon shock velocity. We find that when the field is the result of the growth of the cosmic-ray-driven nonresonant instability alone, the spectrum of electrons and protons released by a supernova remnant are indeed different; however, such a difference becomes appreciable only at energies ≳100−1000 GeV, while observations of the electron spectrum require such a difference to be present at energies as low as ∼10 GeV. An effect at such low energies requires substantial magnetic field amplification in the late stages of supernova remnant evolution (shock velocity ≪1000 km s−1); this may not be due to streaming instability but rather hydrodynamical processes. We comment on the feasibility of such conditions and speculate on the possibility that the difference in spectral shape between electrons and protons may reflect either some unknown acceleration effect or additional energy losses in cocoons around the sources.
Co-W双金属SWCNT催化纳米粒子的原子尺度结构演化
DOI：
--
发表时间：
2018
期刊：
影响因子：
--
作者：
A. Kumamoto;H. An;T. Inoue;S. Chiashi;Y. Ikuhara;R. Xiang;S. Maruyama
通讯作者：
S. Maruyama
宇宙射线对超新星遗迹演化和动量沉积的影响。
影响因子：
8.6
作者：
R. Diesing;D. Caprioli
通讯作者：
D. Caprioli
改进的加权板技术：模型和结果
DOI：
--
发表时间：
2000
期刊：
影响因子：
--
作者：
F. C. Jones;A. Lukasiak;V. Ptuskin;W. Webber
通讯作者：
W. Webber