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arXiv 1004.0725astro-ph.HE
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脉冲星磁层中的线性加速辐射

Linear acceleration emission in pulsar magnetospheres

Brian Reville, John G. Kirk

摘要:

(focus v.)当带电粒子平行于其速度加速时,会发生线性加速发射。我们评估的光谱和角分布,这种辐射的几种特殊情况下,包括恒定加速度(双曲线运动)的有限持续时间。基于这些结果,我们发现了直线加速器中电子发射的以下一般性质,其可以通过作用在距离L上的电场E来表征:(i)光谱延伸到截止光子能量~ LE^2 MeV,其中E是以Schwinger临界场为单位,L是以电子的康普顿波长为单位。穿过加速器的粒子所发射的总能量与标准拉莫尔公式一致(iii)对于双曲线轨迹,低频谱是平坦的,但通常取决于加速器的细节。我们还表明,线性加速辐射补充曲率辐射在强磁化对形成区域的脉冲星磁层。当加速器的长度L小于曲率光子的形成长度时,它占主导地位,曲率光子的形成长度由磁场线的曲率半径与粒子的洛伦兹因子之比给出。在标准的静态模型对创建区域的线性加速度发射是可以忽略不计的,但它是重要的,在更现实的动力学模型中,加速场波动在一个短的长度尺度。

英文摘要:

(abbrev.) Linear acceleration emission occurs when a charged particle is accelerated parallel to its velocity. We evaluate the spectral and angular distribution of this radiation for several special cases, including constant acceleration (hyperbolic motion) of finite duration. Based on these results, we find the following general properties of the emission from an electron in a linear accelerator that can be characterized by an electric field E acting over a distance L: (i) the spectrum extends to a cut-off photon energy ~ LE^2 MeV, where E is in units of the Schwinger critical field and L in units of the Compton wavelength of the electron. (ii) the total energy emitted by a particle traversing the accelerator is in agreement with the standard Larmor formula (iii) the low frequency spectrum is flat for hyperbolic trajectories, but in general depends on the details of the accelerator. We also show that linear acceleration emission complements curvature radiation in the strongly magnetized pair formation regions in pulsar magnetospheres. It dominates when the length L of the accelerator is less than the formation length of curvature photons, which is given by the ratio of the radius of curvature of the magnetic field lines to the Lorentz factor of the particle. In standard static models of pair creating regions linear acceleration emission is negligible, but it is important in more realistic dynamical models in which the accelerating field fluctuates on a short length-scale.

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