发射X射线的GPS星系宽带光谱的模拟
Modelling the broad-band spectra of X-ray emitting GPS galaxies
摘要：
对GHz峰谱射电星系宽带辐射的研究是研究其活动星系中心kpc大小区域内发生的物理过程的有力工具，在该区域内喷流传播，叶瓣膨胀，与周围的星际介质相互作用。我们最近开发了一个新的动力辐射模型来描述GPS现象的演变（Stawarz等人，2008年）：当相对论性喷流通过ISM传播时，逐渐吞没沿途的窄线发射气体云，膨胀叶的电子数量演变，发射同步加速器光，以及逆康普顿辐射通过上散射的光子场从主机星系和它的活动核。该模型成功地再现了GPS射电源的关键特征，描述了其谱能量分布（SED）随波瓣扩展的演变，预测了重要和复杂的X射线到伽马射线发射。我们在这里应用该模型的宽带SED的一个样本的已知的，X射线发射GPS星系，并表明：（一）自由的吸收机制，使我们能够重现在频率低于营业额的无线电连续;（二）瓣的非热，逆康普顿发射可以解释所观察到的X射线光谱，提供了一个可行的替代热，吸积为主的情况。我们还表明，在我们的样本中，X射线和射电氢柱密度之间的关系，N_H和N_HI，是一个正相关的暗示，这一点，如果得到证实，将支持的情况下，高能量发射叶。
英文摘要：
The study of the broad-band emission of GHz-Peaked-Spectrum (GPS) radio galaxies is a powerful tool to investigate the physical processes taking place in the central, kpc-sized region of their active hosts, where the jets propagate and the lobes expand, interacting with the surrounding interstellar medium (ISM). We recently developed a new dynamical-radiative model to describe the evolution of the GPS phenomenon (Stawarz et al. 2008): as the relativistic jets propagate through the ISM, gradually engulfing narrow-line emitting gas clouds along their way, the electron population of the expanding lobes evolves, emitting synchrotron light, as well as inverse-Compton radiation via up-scattering of the photon fields from the host galaxy and its active nucleus. The model, which successfully reproduces the key features of the GPS radio sources as a class, provides a description of the evolution of their spectral energy distribution (SED) with the lobes' expansion, predicting significant and complex X-ray to gamma-ray emission. We apply here the model to the broad-band SED's of a sample of known, X-ray emitting GPS galaxies, and show that: (i) the free-free absorption mechanism enables us to reproduce the radio continuum at frequencies below the turnover; (ii) the lobes' non-thermal, inverse-Compton emission can account for the observed X-ray spectra, providing a viable alternative to the thermal, accretion-dominated scenario. We also show that, in our sample, the relationship between the X-ray and radio hydrogen column densitities, N_H and N_HI, is suggestive of a positive correlation, which, if confirmed, would support the scenario of high-energy emitting lobes.
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