论文标题
Blazars S5 0716+714和PKS 2155-304的不同活动阶段的短期X射线变异性
Short-term X-ray Variability during Different Activity Phases of Blazars S5 0716+714 and PKS 2155-304
论文作者
论文摘要
我们在Blazars S5 0716+714和PKS 2155-304的高X射线可变性阶段期间使用长期暴露{\ it XMM-Newton}数据探索了短期X射线变异性的统计属性。通常，硬度比显示了与源通量状态（计数率）的相关变化，但是在少数情况下，主要是明亮的相位，趋势是复杂的，相关性和抗相关性都表明光谱演化。平稳性测试表明时间序列是非平稳性或具有趋势平稳性。除一个外，没有一个直方图拟合导致正常和对数正态分布的降低-（χ^2 \ sim 1 \），但通常会偏爱正常轮廓。相反，即使在显着性限制不超出显着性限制的情况下，对于所有观测值，Anderson-Darling测试偏向于对数正态的对数正态，而对数正态的测试统计值也比正常正常值较低。没有IDS显示线性RMS-FLUX关系。从广泛使用的不同统计方法中的相反推论表明，需要进行仔细的分析，而硬度比的计数速率的复杂行为表明，在来源的明亮阶段，几个10s kilo秒的光谱演变。在这些情况下，从整个观察结果中提取的光谱对于光谱研究可能没有意义，当然也不是对来源光谱状态的真实表示。
We explored the statistical properties of short-term X-ray variability using long-exposure {\it XMM-Newton} data during high X-ray variability phases of blazars S5 0716+714 and PKS 2155-304. In general, hardness ratio shows correlated variations with the source flux state (count rate), but in a few cases, mainly the bright phases, the trend is complex with correlation and anti-correlation both, indicating spectral evolution. Stationarity tests suggest the time series as non-stationarity or have trend stationarity. Except for one, none of the histograms fit resulted in a reduced-\(χ^2 \sim 1\) for a normal and log-normal profile but a normal profile is favored in general. On the contrary, the Anderson-Darling test favors lognormal with a test-statistic value lower for log-normal over normal for all the observations, even if out of significance limits. None of the IDs show linear RMS-flux relation. The contrary inferences from widely used different statistical methods indicate that a careful analysis is needed while the complex behavior of count rate with hardness ratio suggests spectral evolution over a few 10s of kilo-seconds during bright phases of the sources. In these cases, the spectrum extracted from whole observation may not be meaningful for spectral studies and certainly not a true representation of the spectral state of the source.
