The X-Ray Emissions from the M87 Jet: Diagnostics and Physical Interpretation
The X-Ray Emissions from the M87 Jet: Diagnostics and Physical Interpretation
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DOI：
10.1086/430340
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发表时间：
2005-03
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影响因子：
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通讯作者：
E. Perlman;A. Wilson
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作者：
E. Perlman;A. Wilson
我们重新分析了M87喷气式飞机的钱德拉深度观测结果，该观测结果首次由Wilson & Yang于2002年进行了研究。通过采用还包括图像去卷积的分析链，节点HST-1和I与相邻发射完全分离。我们使用最新的响应函数导出了喷流的空间分辨X射线谱，发现谱形有轻微但显著的变化，αX（Sν-α）的值从~1.2-1.4（在核和节点HST-1、D和C中）到~1.6（在节点F、A和B中）不等。我们利用VLA无线电观测，以及HST成像和偏振测量数据，检查射流的宽带光谱和查询的性质，在射流中的粒子加速。如在以前的论文中所示，一个简单的连续注入模型的同步辐射发射结，其中一个保持恒定的填充因子facc的区域内的粒子被加速和注入粒子的能谱，不能占通量或光谱的X射线发射。相反，我们提出facc是位置和能量的函数，并发现在内部喷流中，facc <$E <$E，在节点A和B中，facc <$E <$E，其中Eγ是发射光子的能量，Ee是发射电子的能量。在这个模型中，注入时的相对论性电子能谱[n（Ee）E]的指数p在所有能量和沿喷流的所有沿着位置都是p = 2.2，与超相对论激波宇宙射线加速模型的预测非常一致（p = 2.23）。在X射线发射的峰值和光学百分比偏振的最小值之间存在强相关性，即，喷流磁场不有序的区域。我们认为，X射线峰值与冲击波相吻合，冲击波加速了X射线发射电子，并导致磁场方向的变化;由于光束平均，因此极化很小。
We reanalyze the deep Chandra observations of the M87 jet, first examined by Wilson & Yang in 2002. By employing an analysis chain that also includes image deconvolution, knots HST-1 and I are fully separated from adjacent emission. We derive the spatially resolved X-ray spectrum of the jet using the most recent response functions and find slight but significant variations in the spectral shape, with values of αX(Sν ∝ ν-α) ranging from ~1.2-1.4 (in the nucleus and knots HST-1, D, and C) to ~1.6 (in knots F, A, and B). We make use of VLA radio observations, as well as HST imaging and polarimetry data, to examine the jet's broadband spectrum and inquire as to the nature of particle acceleration in the jet. As shown in previous papers, a simple continuous injection model for the synchrotron-emitting knots, in which one holds constant both the filling factor facc of the regions within which particles are accelerated and the energy spectrum of the injected particles, cannot account for the flux or spectrum of the X-ray emission. Instead, we propose that facc is a function of both position and energy and find that in the inner jet, facc ∝ E ∝ E, and in knots A and B, facc ∝ E ∝ E, where Eγ is the energy of the emitted photon and Ee is the energy of the emitting electron. In this model, the index p of the relativistic electron energy spectrum at injection [n(Ee) ∝ E] is p = 2.2 at all energies and all locations along the jet, in excellent agreement with the predictions of models of cosmic-ray acceleration by ultrarelativistic shocks (p = 2.23). There is a strong correlation between the peaks of X-ray emission and minima of optical percentage polarization, i.e., regions where the jet magnetic field is not ordered. We suggest that the X-ray peaks coincide with shock waves that accelerate the X-ray-emitting electrons and cause changes in the direction of the magnetic field; the polarization is thus small because of beam averaging.