Modelling of the non-thermal flares in the Galactic microquasar GRS 1915+105
Modelling of the non-thermal flares in the Galactic microquasar GRS 1915+105
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银河微类星体 GRS 1915 105 中非热耀斑的建模
DOI：
10.1046/j.1365-8711.1999.02172.x
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发表时间：
1999
影响因子：
4.8
通讯作者：
F. Aharonian
中科院分区：
文献类型：
--
作者：
A. Atoyan;F. Aharonian
最近在银河系中发现的微类星体为深入了解在不同源群体中观察到的相对论性喷流的物理过程提供了独特的机会。我们研究了从微类星体 GRS 1915+105 的相对论喷射物中检测到的射电耀斑的时间和光谱演化，并提出了一个模型，该模型表明这些耀斑是由相对论电子在快速膨胀的等离子体团（射电云）中遭受辐射、绝热和能量依赖的逃逸损失的同步加速器辐射引起的。找到了膨胀磁化云中相对论电子动力学方程的解析解，并计算了这些电子的同步辐射。将计算出的射电通量与 1994 年 3 月/4 月期间从 GRS 1915+105 的突出耀斑中检测到的射电通量进行详细比较，提供了关于喷射物基本参数的结论性信息，例如磁场的绝对值和时间演化、膨胀速度、相对论性电子连续注入到云中的速率以及它们从云层中依赖于能量的逃逸等。反喷射物的整体运动以及它们之间的不对称程度，还包含有关加速电子的主要能源的重要信息。原则上，这些数据使我们能够区分弓激波驱动的等离子体团和相对论磁化风驱动的等离子体团的情况。假设喷射物中的电子可以被加速到非常高的能量，我们还计算了在从无线电频率到极高能 γ 射线的宽带耀斑期间可以预期的辐射的同步加速器和逆康普顿分量的通量。
The microquasars recently discovered in our Galaxy offer a unique opportunity for a deep insight into the physical processes in relativistic jets observed in different source populations. We study the temporal and spectral evolution of the radio flares detected from the relativistic ejecta in the microquasar GRS 1915+105, and propose a model that suggests that these flares are caused by synchrotron radiation of relativistic electrons suffering radiative, adiabatic and energy-dependent escape losses in fast-expanding plasmoids (radio clouds). Analytical solutions to the kinetic equation for relativistic electrons in the expanding magnetized clouds are found, and the synchrotron radiation of these electrons is calculated. Detailed comparison of the calculated radio fluxes with the ones detected from the prominent flare of GRS 1915+105 during 1994 March/April provides conclusive information on the basic parameters in the ejecta, such as the absolute values and temporal evolution of the magnetic field, the speed of expansion, the rates of continuous injection of relativistic electrons into and their energy-dependent escape from the clouds, etc. The data from radio monitoring of the pair of resolved ejecta enable unambiguous determination of the parameters of the bulk motion of the counter-ejecta and the degree of asymmetry between them, and also contain important information on the prime energy source for accelerated electrons. These data allow us, in principle, to distinguish between the scenarios of bow-shock powered and relativistic magnetized wind powered plasmoids. Assuming that the electrons in the ejecta can be accelerated up to very high energies, we also calculate the fluxes of the synchrotron and inverse Compton components of the radiation that could be expected during the flares in the broad band from radio frequencies to very high-energy γ-rays.