RUI: Relativistic Compton Scattering in Neutron Star Magenetospheres

最近对软伽玛射线中继器和异常x射线脉冲星的观测提供了更多的数据，证明存在一类表面磁场超过临界场4.4万亿高斯的中子星。这项研究旨在了解强场量子电动力学（QED）过程的作用，如康普顿散射、对产生、光子分裂、回旋加速器和同步加速器辐射在中子星磁球中的作用。在这项研究中，电子和正电子的加速模型将被开发，以提供一个自一致的输入参数的描述，以模拟从磁层发射x射线和伽马射线的蒙特卡罗级联模型。主要的工作将是研究相对论性康普顿散射与其他QED过程的作用，建立精确的QED散射截面的近似表达式，并将其纳入一个完整的加速级联模型。以往的研究假设康普顿散射可以用共振下方和共振处的非相对论性康普顿散射截面（汤姆森极限）或共振上方散射的Klein-Nishina截面来充分描述。因此，这些研究没有包括强磁场的影响。由于这些过程高度依赖于相互作用光子的偏振，因此将研究每个QED过程的偏振微分率。将模拟软伽玛射线中继器、异常x射线脉冲星、高场伽玛射线脉冲星、PSR 1509-58和PSR 0656+14以及蟹状星云、帆状星云和Geminga脉冲星的脉冲轮廓和相位相关光谱，并与康普顿伽玛射线天文台（CGRO）、罗西x射线定时探测器（RXTE）和宇宙学和天体物理学高级卫星（ASCA）观测到的脉冲轮廓和相位相关光谱进行比较。计算出的由成对产生的正电子返回到地表的极帽加热产生的热x射线辐射将与伦琴卫星（ROSAT）的观测结果和即将于1999年发射的钱德拉x射线天文台的测量结果进行比较。对逆康普顿散射过程的强场效应的研究将有助于深入了解与各种脉冲星现象相关的粒子-光子相互作用，包括软伽玛射线中继器的爆发光谱和热辐射通过中子星大气的传输。

Abstract - Gonthier AST 9876670The recent observations of soft gamma-ray repeaters and anomalous X-ray pulsars furnish data for greater evidence of the existence of a class of neutron stars with surface magnetic fields exceeding the critical field of 4.4 ten thousand billion Gauss. This research effort seeks to understand the role of strong-field, quantum electrodynamic (QED) processes such as Compton scattering, pair production, photon splitting, and cyclotron and synchrotron radiation in the magnetospheres of neutron stars. In this study, an acceleration model of electrons and positrons will be developed to provide a self-consistent description of the input parameters to a Monte Carlo cascade model that simulates the emission of X-rays and gamma rays from the magnetosphere. The main effort will be to study the role of relativistic Compton scattering as it operates with other QED processes, to develop approximate expressions of the exact QED scattering cross section and incorporate them in a full acceleration-cascade model. Previous studies have assumed that Compton scattering can be adequately described by the non-relativistic Compton scattering cross section (Thomson limit) below resonance and at the resonance, or the Klein-Nishina cross section for scattering above the resonance. Consequently, these studies have not included the effects of the strong magnetic fields. Since these processes are highly dependent upon the polarization of the interacting photons, polarized differential rates for each QED process will be investigated. Pulse profiles as well as phase dependent spectra of the soft gamma-ray repeaters, anomalous X-ray pulsars, the high field gamma-ray pulsars, PSR 1509-58 and PSR 0656+14, along with the Crab, Vela and Geminga pulsars will be simulated and compared with those observed by the Compton Gamma-Ray Observatory (CGRO), the Rossi X-ray Timing Explorer (RXTE) and the Advanced Satellite for Cosmology and Astrophysics (ASCA). The calculated thermal X-ray emission from polar cap heating by pair-created positrons returning to the surface will be compared with the observations of Roentgen Satellite (ROSAT) and upcoming measurements from the Chandra X-ray Observatory that is scheduled to be launched in 1999. The study of the strong field effects on the inverse Compton scattering process will provide insight into the particle-photon interactions associated with a variety of pulsar phenomena, including burst spectra of soft gamma-ray repeaters and the transport of thermal radiation through neutron star atmospheres.