Constraints on the energetics and plasma composition of relativistic jets in FR II sources
Constraints on the energetics and plasma composition of relativistic jets in FR II sources
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DOI：
10.1111/j.1365-2966.2004.07511.x
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发表时间：
2003-12
影响因子：
4.8
通讯作者：
M. Kino;F. Takahara
中科院分区：
文献类型：
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作者：
M. Kino;F. Takahara
我们探索FR II源的能量和等离子体成分使用一种新的简单的方法相结合的冲击动力学和辐射光谱。这些热点与喷流的反向激波区一致。在考虑团簇内热介质有限压力的一维激波跳跃条件下，我们估计了热点中热粒子和非热粒子之和的静止质量和能量密度。独立地，基于同步辐射自康普顿（SSC）模型，我们利用热点的多频辐射谱估计了非热电子的数量和能量密度。我们施加的条件，得到的静止质量，内部能量和非热电子的数密度应低于由冲击动力学确定的总粒子。我们将此方法应用于天鹅座A。我们研究了纯电子-正电子对等离子体（第一种情况），纯电子-质子等离子体与单独热化（第二种情况）和纯电子-质子等离子体在热平衡（第三种情况）的三种极端情况。通过对天鹅座A和3C 123的详细SSC分析，我们发现非热电子的能量密度大约是磁场能量密度的10倍。我们发现，情况III是不可接受的，因为预测的光子光谱不给一个很好的配合观察到的。我们发现，情况II也可以排除，因为非热电子的数密度超过了总数密度。因此，我们发现，在这三种情况中，只有纯e ±血浆（情况I）是可接受的。喷流的总动能和电子加速效率也受到非热粒子和总粒子内能密度的制约。
We explore the energetics and plasma composition in FR II sources using a new simple method of combining shock dynamics and radiation spectrum. The hotspots are identified with the reverse-shocked region of jets. With the 1D shock jump conditions taking account of the finite pressure of hot intracluster medium (ICM), we estimate the rest mass and energy densities of the sum of thermal and non-thermal particles in hotspots. Independently, based on the Synchrotron Self-Compton (SSC) model, we estimate the number and energy densities of non-thermal electrons using the multifrequency radiation spectrum of hotspots. We impose the condition that the obtained rest mass, internal energy and number densities of non-thermal electrons should be lower than those of the total particles determined by shock dynamics. We apply this method to Cygnus A. We examine three extreme cases of pure electron-positron pair plasma (Case I), pure electron-proton plasma with separate thermalization (Case II) and pure electron-proton plasma in thermal equilibrium (Case III). By detailed SSC analysis for Cygnus A and 3C 123, we find that the energy density of non-thermal electrons is about 10 times larger than that of the magnetic field. We find that Case III is not acceptable because predicted photon spectra do not give a good fit to the observed one. We find that Case II can also be ruled out because the number density of non-thermal electrons exceeds that of the total number density. Hence we find that only pure e ± plasma (Case I) is acceptable among the three cases. Total kinetic power of jet and electron acceleration efficiency are also constrained by internal energy densities of non-thermal and total particles.