LS 5039是一个发射高能和极高能伽马射线的星系双星系统。伽马射线通量调制的轨道周期和TeV的光曲线形状的光子-光子湮灭。所观察到的非常高的能量调制可以用一个简单的轻子模型来重现，但无法解释HESS在超级合点检测到的通量，在那里伽马射线被完全吸收。来自电子-正电子对级联的贡献可能是强的，并且在优合处超过初级通量。所产生的电子对可以通过磁场各向同性化，从而产生三维级联。本文的目的是研究LS 5039中这对级联的γ射线辐射。这个附加的分量可以解释系统中上合点的HESS观测。本文提出了一种计算三维级联辐射的半解析和蒙特卡罗方法，并应用于双星系统。三维级联辐射在TeV光变曲线中的每个轨道相位都有显着的贡献，并且在接近高级结合处占主导地位。伽马射线调制的振幅在轨道倾角约为40度时能正确地再现。初级对应该被注入接近紧凑的对象的位置，否则调制的形状没有解释。此外，X射线中级联的同步加速器发射将环境磁场限制在10 G以下。在LS 5039中，HESS观测到的TeV通量可以用三维对级联辐射来解释，但在低通量下的极高能谱仍难以解释。
英文摘要：
LS 5039 is a Galactic binary system emitting high and very-high energy gamma rays. The gamma-ray flux is modulated on the orbital period and the TeV lightcurve shaped by photon-photon annihilation. The observed very-high energy modulation can be reproduced with a simple leptonic model but fails to explain the flux detected by HESS at superior conjunction, where gamma rays are fully absorbed. The contribution from an electron-positron pair cascade could be strong and prevail over the primary flux at superior conjunction. The created pairs can be isotropized by the magnetic field, resulting in a three-dimensional cascade. The aim of this article is to investigate the gamma ray radiation from this pair cascade in LS 5039. This additional component could account for HESS observations at superior conjunction in the system. A semi-analytical and a Monte Carlo method for computing three-dimensional cascade radiation are presented and applied in the context of binaries. Three-dimensional cascade radiation contributes significantly at every orbital phase in the TeV lightcurve, and dominates close to superior conjunction. The amplitude of the gamma-ray modulation is correctly reproduced for an inclination of the orbit of about 40 degrees. Primary pairs should be injected close to the compact object location, otherwise the shape of the modulation is not explained. In addition, synchrotron emission from the cascade in X-rays constrains the ambient magnetic field to below 10 G. The radiation from a three-dimensional pair cascade can account for the TeV flux detected by HESS at superior conjunction in LS 5039, but the very-high energy spectrum at low fluxes remains difficult to explain in this model.
Modeling the high-energy radiation in gamma-ray binaries
伽玛射线双星是银河系中的轨道调制伽玛射线源，可以在GeV和TeV能量下探测到。高能辐射可能来自年轻脉冲星注入的高能电子与来自大质量伴星的光子的相互作用。我们提出了一个模型的高能量辐射的产生，其中考虑了发射，吸收和对级联。费米太空望远镜对LS I +61 303的最新观测显示，在几个GeV的能量下，光谱出现指数截止，与伽马-伽马吸收不一致。电子辐射在GeV和TeV可能有两个不同的起源。我们调查是否从未受冲击的脉冲星风的发射解释了在LS I +61 303的GeV分量。
A model for the two component gamma-ray spectra observed from the gamma-ray binaries
用卫星和切伦科夫望远镜对两个著名的双星系统（LS 5039和LS I +61 303）进行观测，发现宽频带的$γ$射线谱似乎显示出两个分量，第一个在GeV能量处，在几个GeV处显示出指数截止，第二个在TeV能量处，这与从GeV能量范围外推的谱不太吻合。我们建议，这样的两个组件的频谱是由两个人口的电子出现在二元系统作为一个双激波结构分离的接触不连续的加速的结果。这种结构是在双星系统中由于脉冲星和大质量星风的相互作用而产生的。来自脉冲星和大质量恒星侧面的冲击具有不同的特性，允许电子加速到不同的最大能量。这两个电子群体产生由恒星辐射的逆康普顿（IC）散射引起的双分量$γ$射线谱。用各向异性的IC $e^\pm$对级联模型计算了脉冲星在近星和近星通道的位置，证实了从LS I +61 303观测到的高能辐射特征。
An Accurate Modeling of Nano-hertz Gravitational Wave Signal from Eccentric Supermassive Binary Black Holes: An Essential Step Toward a Robust Discovery
