ON THE ORIGIN OF THE γ-RAY/OPTICAL LAGS IN LUMINOUS BLAZARS
ON THE ORIGIN OF THE γ-RAY/OPTICAL LAGS IN LUMINOUS BLAZARS
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DOI：
10.1088/0004-637x/760/2/129
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发表时间：
2012-10
期刊：
影响因子：
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通讯作者：
M. Janiak;M. Sikora;K. Nalewajko;R. Moderski;G. Madejski
中科院分区：
文献类型：
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作者：
M. Janiak;M. Sikora;K. Nalewajko;R. Moderski;G. Madejski
耀变体是一种强烈的变化源，偶尔会在不同的能量带中显示出壮观的耀斑。这些耀斑经常但不总是相关的。在许多情况下，发现光学耀斑的峰值相对于γ射线峰值有一定的延迟。Hayashida等人在3C 279中发现了这种延迟的一个值得注意的例子，并解释为外部辐射场的能量密度比磁能密度随距离的下降更陡。在本文中，我们证明，在一般情况下，取决于各自的能量密度分布沿着射流，这样的滞后可以有两个符号，他们可以发生这些能量密度的任何比例。我们研究这些能量密度的比率在一个最大的能量耗散在射流的距离，在其梯度，以及在移动源内的相对论电子注入的时间分布上的滞后的依赖性。我们展示了这种滞后是多么突出，以及它们的预期时间尺度。我们认为，这种滞后的研究可以提供一个强有力的工具，以解决相对论喷流的结构和辐射环境。作为一个例子，我们对3C 279中观察到的滞后进行了建模，表明在这个物体中，耀斑是在距离中心黑洞几个秒差距的距离处产生的，这与我们之前基于光谱和光学偏振特性的推断一致。
Blazars are strongly variable sources that occasionally show spectacular flares visible in various energy bands. These flares are often, but not always, correlated. In a number of cases, the peaks of optical flares are found to be somewhat delayed with respect to the γ-ray peaks. One notable example of such a delay was found in 3C 279 by Hayashida et al. and interpreted as a result of steeper drop with a distance of the energy density of an external radiation field than of the magnetic energy density. In this paper, we demonstrate that, in general, depending on the respective energy density profile along the jet, such lags can have both signs and that they can take place for any ratio of these energy densities. We study the dependence of such lags on the ratio of these energy densities at a distance of a maximal energy dissipation in a jet, on their gradients, as well as on the time profile of the relativistic electron injection within the moving source. We show how prominent such lags can be, and their expected timescales. We suggest that studies of such lags can provide a powerful tool to resolve the structure of relativistic jets and their radiative environment. As an example we model the lag observed in 3C 279, showing that in this object the flare is produced at a distance of a few parsecs from the central black hole, consistent with our previous inferences based on the spectra and optical polarization properties.