RUI: Relativistic Compton Scattering in Neutron Star Magenetospheres

最近对软伽马射线中继器和反常X射线脉冲星的观测为一类表面磁场超过4.4万亿高斯临界场的中子星的存在提供了更多的证据。这项研究试图了解强场、量子电动力学(QED)过程在中子星磁层中的作用，如康普顿散射、对产生、光子分裂以及回旋和同步辐射。在这项研究中，将发展一个电子和正电子的加速模型，以提供对蒙特卡罗级联模型输入参数的自洽描述，该模型模拟从磁层发射的X射线和伽马射线。主要的工作将是研究相对论康普顿散射与其他QED过程的作用，推导出精确的QED散射截面的近似表达式，并将它们纳入一个完整的加速-级联模型中。以前的研究假设康普顿散射可以用共振以下和共振时的非相对论康普顿散射截面(Thomson极限)来描述，或者在共振以上用Klein-Nishina散射截面来描述。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过程的偏振差分率。将模拟软伽马射线中继器、反常X射线脉冲星、高场伽马射线脉冲星PSR 1509-58和PSR 0656+14以及Crab、Vela和Geminga脉冲星的脉冲轮廓和相变光谱，并与康普顿伽马射线天文台(CGRO)、Rossi X射线定时探测器(RXTE)和高级宇宙学和天体物理卫星(ASCA)的观测结果进行比较。由返回地表的正电子对产生的极帽加热所计算的热X射线辐射将与伦琴卫星(ROSAT)的观测结果以及计划于1999年发射的钱德拉X射线观测站即将进行的测量结果进行比较。对逆康普顿散射过程中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，包括软伽马射线中继器的爆发谱和热辐射在中子星大气中的传输。

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.