论文标题
脉冲星云中的扩散冲击加速器的最大光谱
Maximally-hard spectra from diffusive shock-acceleration in pulsar-wind nebulae
论文作者
论文摘要
尚未了解导致脉冲星（pwne）异常硬无线电光谱的过程。来自文献的$ 29 $旋转中的无线电光子光谱指数显示大约正常，$α= 0.2 \ pm0.2 $分布。我们提供了$ \ sim3σ$证据，证明了质量＃的独特子群，其硬光谱$α= 0.01 \ pm0.06 $在终止冲击附近，并且在其他地方明显柔和，这可能是由于最近撤离了冲击周围环境。这样的光谱，尤其是在硬种群中，提出了一个费米的过程，例如在极端情况下，$α= 0 $限制。我们表明，该极限已接近足够各向异性的小角度散射，在冲击的两侧增强了接近冲击锋的颗粒。在上游，光谱硬化主要与增强的能量增益相关，可能是由相同的光束颗粒越过冲击冲击的。在下游，主要效果是逃逸概率的降低，但这将加速度效率降低至$ \ lysSim25 \％$，$α= 0.3 $和$ \ lyssim1 \％\％$ $ $α= 0.03 $。
The processes leading to the exceptionally hard radio spectra of pulsar-wind nebulae (PWNe) are not yet understood. Radio photon spectral indices among $29$ PWNe from the literature show an approximately normal, $α=0.2\pm0.2$ distribution. We present $\sim 3σ$ evidence for a distinct sub-population of PWNe, with a hard spectrum $α=0.01\pm0.06$ near the termination shock and significantly softer elsewhere, possibly due to a recent evacuation of the shock surroundings. Such spectra, especially in the hard sub-population, suggest a Fermi process, such as diffusive shock acceleration, at its extreme, $α=0$ limit. We show that this limit is approached for sufficiently anisotropic small-angle scattering, enhanced on either side of the shock for particles approaching the shock front. In the upstream, the spectral hardening is mostly associated with an enhanced energy gain, possibly driven by the same beamed particles crossing the shock. Downstream, the main effect is a diminished escape probability, but this lowers the acceleration efficiency to $\lesssim25\%$ for $α=0.3$ and $\lesssim1\%$ for $α=0.03$.
