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arXiv 0906.1691astro-ph.HE
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类蟹状星云中的粒子加速和极高能gamma-ray辐射

On particle acceleration and very high energy gamma-ray emission in Crab-like pulsars

Zaza Osmanov, Frank M. Rieger

摘要:

高能带电粒子的起源和甚高能γ射线辐射的产生仍然是现代脉冲星物理中的一个挑战性问题。通过应用一个玩具模型,我们探讨了在富含等离子体的脉冲星磁层中靠近光表面的同向旋转带电粒子的加速度,并在适合于克拉布型脉冲星的条件下研究了它们与磁场和光子场的相互作用。分析了类单极磁场几何中粒子的离心加速,确定了共转、逆康普顿相互作用和曲率辐射反应对粒子离心加速效率的限制。我们推导出最大粒子能量的表达式,并提供相应的高能量曲率和逆康普顿功率输出的估计。结果表明,对于类蟹状星云,电子洛伦兹因子可达$γ\sim 10^7$,使热光子逆康普顿(Klein-Nishina)上散射到TeV能量,最大亮度输出为$\sim10^{31}$ erg/s.另一方面,曲率辐射将导致高达$\sim(10^{34}-10^{35})$ erg/s的强GeV发射输出,对于低于$\sim 50$ GeV的光子能量,其朝向更高能量准指数地减小。根据所呈现的结果,预期只有年轻的类星体是可检测到VHE $γ$射线发射的场所。

英文摘要:

The origin of very energetic charged particles and the production of very high-energy (VHE) gamma-ray emission remains still a challenging issue in modern pulsar physics. By applying a toy model, we explore the acceleration of co-rotating charged particles close to the light surface in a plasma-rich pulsar magnetosphere and study their interactions with magnetic and photon fields under conditions appropriate for Crab-type pulsars. Centrifugal acceleration of particles in a monopol-like magnetic field geometry is analyzed and the efficiency constraints, imposed by corotation, inverse Compton interactions and curvature radiation reaction are determined. We derive expressions for the maximum particle energy and provide estimates for the corresponding high-energy curvature and inverse Compton power outputs. It is shown that for Crab-like pulsars, electron Lorentz factor up to $γ\sim 10^7$ can be achieved, allowing inverse Compton (Klein-Nishina) up-scattering of thermal photons to TeV energies with a maximum luminosity output of $\sim10^{31}$ erg/s. Curvature radiation, on the other hand, will result in a strong GeV emission output of up to $\sim(10^{34}-10^{35})$ erg/s, quasi-exponentially decreasing towards higher energies for photon energies below $\sim 50$ GeV. Accordingly to the results presented only young pulsars are expected to be sites of detectable VHE $γ$-ray emission.

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