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arXiv 0710.0968astro-ph
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来自二进制LS 5039的gamma-ray发射的调制

The modulation of the gamma-ray emission from the binary LS 5039

G. Dubus, B. Cerutti, G. Henri

摘要:

伽马射线双星是由大质量恒星和致密天体组成的一类新的超高能光子源。伽马射线是由在致密天体附近加速的VHE电子对恒星光的逆康普顿散射产生的。LS 5039的VHE发射显示出轨道调制。逆康普顿谱取决于电子静止系中入射光子和出射光子之间的角度。由于观察者看到恒星和电子的角度随轨道而变化,因此可以预期光谱的相位依赖性。假设电子连续注入,计算LS 5039的相位相关光谱。电子分布的形状取决于注入的幂律和磁场强度。各向异性散射产生硬发射在劣质的结合,当衰减由于对生产的VHE伽马射线的星光是最小的。计算的光变曲线和光谱提供了很好的拟合HESS和EGRET观测,除了在最大衰减阶段,对级联发射可能是显着的HESS。详细的预测是在GLAST能量范围内的调制。近星点的磁场强度为0.8 ± 0.2G。各向异性逆康普顿散射在LS 5039中起着重要作用。推导出的磁场强度,注入能量和斜率表明旋转动力脉冲星风星云。γ射线双星是研究小尺度γ星环境的一个很有前途的源。

英文摘要:

Gamma-ray binaries, composed of a massive star and compact object, have been established as a new class of sources of very high energy (VHE) photons. The gamma-rays are produced by inverse Compton scattering of the stellar light by VHE electrons accelerated in the vicinity of the compact object. The VHE emission from LS 5039 displays an orbital modulation. The inverse Compton spectrum depends on the angle between the incoming and outgoing photon in the electron rest frame. Since the angle at which an observer sees the star and electrons changes with the orbit, a phase dependence of the spectrum is expected. The phase-dependent spectrum of LS 5039 is calculated, assuming a continuous injection of electrons. The shape of the electron distribution depends on the injected power-law and on the magnetic field intensity. Anisotropic scattering produces hard emission at inferior conjunction, when attenuation due to pair production of the VHE gamma-rays on star light is minimum. The computed lightcurve and spectra provide good fits to the HESS and EGRET observations, except at phases of maximum attenuation where pair cascade emission may be significant for HESS. Detailed predictions are made for a modulation in the GLAST energy range. The magnetic field intensity at periastron is 0.8+-0.2 G. Anisotropic inverse Compton scattering plays a major role in LS 5039. The derived magnetic field intensity, injection energy and slope suggest a rotation-powered pulsar wind nebula. Gamma-ray binaries are promising sources to study the environment of pulsars on small scales.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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