Electron–positron pairs in blazar jets and γ-ray loud radio galaxies
Electron–positron pairs in blazar jets and γ-ray loud radio galaxies
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DOI：
10.1111/j.1745-3933.2012.01280.x
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发表时间：
2012-05
影响因子：
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通讯作者：
G. Ghisellini
中科院分区：
文献类型：
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作者：
G. Ghisellini
河外相对论性喷流的物质含量仍然是一个未解决的问题。有强烈的反对纯电子-正电子对喷流的观点，但电子对的数量可能比与质子相关的电子多10-20倍。这影响了射流动能的估计，通过减少相同的因素，以及粒子加速机制传递给轻子的总能量。在与我们在耀变体中看到的高能γ射线发射相同的喷射区中，不能产生双星对，因为对产生的双星对的再处理会产生过多的x射线通量。大量的对产生可能发生在仍在加速的射流的内部区域，那里的总体洛伦兹因子很小。研究发现，内部区域可以产生足够数量的γ射线对，以补充喷射的大部分发光区域，但前提是内部喷射的γ射线亮度在~ 1 MeV时高于1044 erg s−1。由于光束是适度的，这种发射可以在大视角下观测到，并且可以在射电星系和叶状主导类星体中检测到，对于红移z= 0.1的源，通量水平为10−12-10−11 erg cm−2 s−1。
The matter content of extragalactic relativistic jets is still an unsolved issue. There are strong arguments against pure electron–positron pair jets, but pairs could outnumber the electrons associated with protons by a factor of 10–20. This impacts on the estimate of the jet kinetic power, by reducing it by the same factor, and on the total energy delivered to leptons by the particle acceleration mechanism. Pairs cannot be created in the same jet zone responsible for the high-energy γ-ray emission we see in blazars, because the reprocessing of the created pairs would overproduce the X-ray flux. Copious pair creation could occur in the inner zone of the still accelerating jet, where the bulk Lorentz factor is small. It is found that the inner zone can produce a sufficient number of pairs to replenish the zone of the jet where most of the luminosity is emitted, but only if the γ-ray luminosity of the inner jet is above 1044 erg s−1 at ∼1 MeV. Since the beaming is modest, this emission can be observed at large viewing angles, and detected in radio galaxies and lobe-dominated quasars at the flux level of 10−12–10−11 erg cm−2 s−1 for a source at a redshift z= 0.1.