Nonthermal Radiation from Pulsar Wind Nebulae
Nonthermal Radiation from Pulsar Wind Nebulae
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DOI：
10.1086/527466
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发表时间：
2008-04
期刊：
影响因子：
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通讯作者：
Lizhen Zhang;S. B. Chen;J. Fang
中科院分区：
文献类型：
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作者：
Lizhen Zhang;S. B. Chen;J. Fang
用简化的时间依赖注入模型研究了脉冲星风星云（PWNe）从射电到TeV γ射线能量的非热发射。在该模型中，由一个自旋功率为L(t)的中心脉冲星驱动的相对论性粒子风被吹入周围介质，形成激波，通过PWN中的费米加速机制将粒子加速到非常高的能量。因此，PWN中的相对论性粒子由两部分组成，一部分直接来自脉冲星磁层，另一部分来自PWN中的激波加速度。模型PWN谱遵循不同指标的破缺幂律和破缺能Eb。加速粒子通过同步辐射和软光子场的逆康普顿散射产生非热光子。我们将这个模型应用到蟹状星云、MSH 15-52中的PWN和HESS J1825-137中，它们都被发现发射出非常高能（VHE）光子。结果表明：(1)该模型可以再现蟹状星云从射电到VHE γ射线的观测数据，其中射电到中能γ射线的发射来自于同步加速器发射，而高能光子主要来自于同步加速器光子上高能电子的逆康普顿散射；(2) MSH 15-52和HESS J1825-137中PWN的TeV发射主要来自高能电子对红外光子的逆康普顿散射。
We study the nonthermal emission of pulsar wind nebulae (PWNe) from radio to TeV γ-ray energies with a simplified time-dependent injection model. In this model, a relativistic wind of particles driven by a central pulsar with a spin-down power L(t) is blown into the ambient medium and a shock wave is formed, which accelerates the particles to very high energies through the Fermi acceleration mechanism in the PWN. The relativistic particles in the PWN therefore consist of two components, one coming directly from the pulsar magnetosphere and the other from shock acceleration in the PWN. The model PWN spectra follow a broken power law with different indices and a break energy Eb. The accelerated particles produce nonthermal photons through synchrotron radiation and inverse Compton scattering off soft photon fields. We apply this model to the Crab Nebula, the PWN in MSH 15–52, and HESS J1825–137, which have all been found to emit very high energy (VHE) photons. Our results indicate that (1) the observed data, ranging from radio to VHE γ-rays, for the Crab Nebula can be reproduced by this model, where the emission from radio to medium-energy γ-rays is from the synchrotron emission due to the injected electrons, whereas the high-energy photons primarily come from inverse Compton scattering of the high-energy electrons on synchrotron photons; and (2) the TeV emission from the PWN in MSH 15–52 and HESS J1825–137 mainly comes from the inverse Compton scattering of the high-energy electrons on infrared photons.