Escape of cosmic rays from perpendicular shocks in the circumstellar magnetic field
Escape of cosmic rays from perpendicular shocks in the circumstellar magnetic field
复制标题
DOI：
10.1103/physrevd.106.123025
复制
发表时间：
2022-07
影响因子：
5
通讯作者：
Shoma F. Kamijima;Y. Ohira
中科院分区：
文献类型：
--
作者：
Shoma F. Kamijima;Y. Ohira
研究了球面激波在具有Parker螺旋磁场的星周介质中，宇宙线从垂直激波区逃逸的过程。超新星遗迹(SNR)垂直激波中的扩散激波加速有望在没有上游磁场放大的情况下将CRS加速到PeV。红超巨星(RSGs)和Wolf-Rayet(WR)恒星被认为是这项工作的前身。我们进行了测试粒子模拟，以研究上游区域的逃逸过程和逃逸限制的最大能量，在没有磁场放大的情况下，该区域使用了从RSGS和WR星的观测中预期的磁场强度和自转周期。我们发现粒子在沿赤道或极地运动时逃逸到远上游区域，当SNR传播到RSGS和WR恒星的自由风区时，最大能量约为10-100RmTeV。在大多数情况下，逃逸限制的最大能量是由赤道和极地之间的电势差给出的。如果前身是倾斜的旋转体，并且SNR处于超新星爆发后的早期阶段，逃逸限制的最大能量受到波状电流片的半波长的限制。此外，对于RSGs，我们还指出，如果在大多数RSGs中保持较强的磁场强度，在风区加速的CRS的亮度足以提供超过$10rmTeV的观测CR通量。就CR值而言，传播到WR星自由风的信噪比对PeVCRS有贡献。只要在SNR激波附近没有磁场放大作用，最大能量由风区的磁场强度决定，而磁场强度取决于RSG和WR星的自转周期、恒星风和表面磁场。因此，我们需要观察这些量来理解CRS的起源。
We investigate the escape process of cosmic rays (CRs) from perpendicular shock regions of a spherical shock propagating to a circumstellar medium with the Parker-spiral magnetic field. The diffusive shock acceleration in perpendicular shocks of supernova remnants (SNRs) is expected to accelerate CRs up to PeV without upstream magnetic field amplification. Red supergiants (RSGs) and Wolf-Rayet (WR) stars are considered as progenitors in this work. We perform test particle simulations to investigate the escape process and escape-limited maximum energy without magnetic field amplification in the upstream region, where the magnetic field strength and rotation period expected from observations of RSGs and WR stars are used. We show that particles escape to the far upstream region while moving along the equator or poles and the maximum energy is about $10-100~{\rm TeV}$ when SNRs propagate to free wind regions of RSGs and WR stars. In most cases, the escape-limited maximum energy is given by the potential difference between the equator and pole. If progenitors are oblique rotators and SNRs are in the early phase just after the supernova explosion, the escape-limited maximum energy is limited by the half wavelength of the wavy current sheet. In addition, for RSGs, we show that the luminosity of CRs accelerated in the wind region is sufficient to supply the observed CR flux above $10~{\rm TeV}$ if a strong magnetic field strength is sustained in most RSGs. In terms of the CR luminosity, SNRs propagating to the free wind of WR stars can contribute to PeV CRs. As long as no magnetic field amplification works around SNR shocks, the maximum energy is decided by the magnetic field strength in the wind region, which depends on the rotation period, stellar wind, and surface magnetic field of RSGs and WR stars. Therefore, we need to observe these quantities to understand the origin of CRs.