论文标题
关于MRK 421的平坦无线电频谱的解释
An explanation about the flat radio spectrum for Mrk 421
论文作者
论文摘要
众所周知，平坦的无线电光谱是Blazars光谱能量分布中的共同特性。尽管单区Leptonic模型通常成功地解释了多波带发射，但它们在重现无线电频谱方面存在问题。在对MRK 421的研究中，单区模型表明，为了避免过量产生无线电通量，最小电子Lorentz因子至少应大于几百，甚至考虑到同步体自动吸收效应。该结果表明该模型预测MRK 421无线电带中的光谱指数应为-1/3。在此结果的基础上，假设有一个被忽视的区域也将贡献无线电发射，并且其电子能量指数自然源自最简单的一阶费米加速机制，我们可以获得叠加的平坦无线电频谱。在本文中，提出了一个两区模型来再现MRK 421的静态状态光谱能分布。除了考虑到传统辐射区的发射外，我们还考虑了从加速区加速粒子在冲击前方加速的加速度的发射。通过本模型，我们的拟合结果表明，MRK 421的低频平坦无线电光谱可以解释为加速区和辐射区的同步加速器发射的叠加。
It is well known that the flat radio spectrum is a common property in the spectral energy distribution of blazars. Although the one-zone leptonic models are generally successful in explaining the multi-wave band emission, they are problematic in reproducing the radio spectrum. In the study of Mrk 421, one-zone models suggest that in order to avoid overproducing the radio flux, the minimum electron Lorentz factor should be larger than a few hundred at least, even considering the synchrotron self-absorption effect. This result suggests that the model predicted spectral index in the radio band of Mrk 421 should be -1/3. On the basis of this result, by assuming there is a neglected region that will also contribute the radio emission and its electron energy index is naturally originate from the simplest first-order Fermi acceleration mechanism, we can get a superimposed flat radio spectrum. In this paper, a two-zone model is proposed to reproduce the quiescent state spectral energy distribution of Mrk 421. In addition to taking into account the emission from a conventional radiation zone, we further consider the emission from the acceleration zone in which particles are accelerated at a shock front. With the present model, our fitting result suggests that the low frequency flat radio spectrum of Mrk 421 might be explained as a superposition of the synchrotron emission from acceleration zone and radiation zone.
