2005-2014年期间带Suzaku的TeV Blazar PKS 2155-304的X射线日内变异性
X-ray Intraday Variability of the TeV Blazar PKS 2155-304 with Suzaku During 2005-2014
摘要：
我们检查了朱雀卫星在整个运行期间对TeV发射高同步加速器峰值耀变体PKS 2155-304进行的13次定点观测。我们发现耀变体在光变曲线的软带（0.8 - 1.5 keV）和硬带（1.5 - 8.0 keV）中表现出大幅度的日内变化。使用硬度比估计日内时间尺度上的光谱变化。耀变体通常在更亮时变得更硬，反之亦然，遵循高同步辐射峰值耀变体的典型行为。在总能量（0.8 - 8.0 keV）的13条光变曲线中，有11条的功率谱密度（PSD）分析被发现是红噪声占主导地位的，其幂律谱指数范围很大，从-2.81到-0.88。软带和硬带之间的所有13条光变曲线的离散关联函数分析表明，它们具有很好的相关性，并且在零滞后处或非常接近零滞后处达到峰值。这表明，软带和硬带的辐射可能是同空间的，并且是由相同的轻子群发射的。考虑到通量与变化的时间尺度，我们发现没有相关性的日内时间尺度，这意味着X射线发射从PKS 2155-304不是由简单的多普勒因子的变化占主导地位。我们简要地讨论了最有可能的发射机制，负责所观察到的通量和光谱的变化，并放置在最有可能的情况下发射X射线的电子的磁场强度和洛伦兹因子的约束。
英文摘要：
We have examined 13 pointed observations of the TeV emitting high synchrotron peak blazar PKS 2155-304, taken by the Suzaku satellite throughout its operational period. We found that the blazar showed large-amplitude intraday variabilities in the soft (0.8 - 1.5 keV) and the hard (1.5 - 8.0 keV) bands in the light curves. Spectral variability on intraday timescales is estimated using the hardness ratio. The blazar usually becomes harder when brighter and vice versa, following the typical behavior of high synchrotron peak blazars. The power spectral density (PSD) analyses of 11 out of 13 light curves in the total energy (0.8 - 8.0 keV) are found to be red-noise dominated, with power-law spectral indices that span a large range, from -2.81 to -0.88. Discrete correlation function analyses of all the 13 light curves between the soft and the hard bands show that they are well correlated and peak at, or very close to, zero lag. This indicates that the emissions in soft and hard bands are probably cospatial and emitted from the same population of leptons. Considering fluxes versus variability timescales, we found no correlation on intraday timescales, implying that X-ray emission from PKS 2155-304 is not dominated by simple changes in the Doppler factor. We briefly discuss the most likely emission mechanisms responsible for the observed flux and spectral variabilities and place constraints on magnetic field strength and Lorentz factors of the electrons emitting the X-rays in the most likely scenario.
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