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arXiv 0801.4547astro-ph
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封闭TeV双星系统次级电子对的非热辐射

Non-thermal emission from secondary pairs in close TeV binary systems

V. Bosch-Ramon, D. Khangulyan, F. A. Aharonian

摘要:

大质量热恒星在其周围产生密集的紫外线(UV)光子场。如果一个非常高能量(VHE)的伽马射线发射体位于恒星附近,那么伽马射线会被恒星光子场吸收,产生次级(电子-正电子)对。我们研究了这些次级电子对在恒星光子和磁场中的宽带辐射。在对恒星风和大质量热星周围磁场的一定假设下,计算了系统中次级对的稳态能量分布及其从射电到γ射线的辐射。在环境磁场(可能足够高以抑制电磁(EM)级联)下,次级对的能量经由同步加速器和产生无线电到伽马射线辐射的单个IC散射辐射。同步辐射光谱能量分布(SED)是硬的,在X射线能量附近达到峰值,并且变得更软。IC SED也很硬,峰值在10 GeV左右,由于同步辐射损失占主导地位,在更高的能量下也变得更软。次级对的无线电发射是中等的,可以作为点状和/或扩展源检测到。在X射线中,次级对同步加速器分量可能占主导地位。在能量<10 GeV时,次级对IC辐射可能是主要的初级伽马射线发射,并可能被下一代仪器探测到。

英文摘要:

Massive hot stars produce dense ultraviolet (UV) photon fields in their surroundings. If a very high-energy (VHE) gamma-ray emitter is located close to the star, then gamma-rays are absorbed in the stellar photon field, creating secondary (electron-positron) pairs. We study the broadband emission of these secondary pairs in the stellar photon and magnetic fields. Under certain assumptions on the stellar wind and the magnetic field in the surroundings of a massive hot star, we calculate the steady state energy distribution of secondary pairs created in the system and its radiation from radio to gamma-rays. Under the ambient magnetic field, possibly high enough to suppress electromagnetic (EM) cascading, the energy of secondary pairs is radiated via synchrotron and single IC scattering producing radio-to-gamma-ray radiation. The synchrotron spectral energy distribution (SED) is hard, peaks around X-ray energies, and becomes softer. The IC SED is hard as well and peaks around 10 GeV, becoming also softer at higher energies due to synchrotron loss dominance. The radio emission from secondary pairs is moderate and detectable as a point-like and/or extended source. In X-rays, the secondary pair synchrotron component may be dominant. At energies <10 GeV, the secondary pair IC radiation may be the dominant primary gamma-ray emission and possibly detectable by the next generation of instruments.

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