论文标题
长期γ-射线的可变性
Long term γ -ray variability of blazars
论文作者
论文摘要
我们使用了Fermi Gamma射线空间望远镜中的数据来表征Blazars在月份时间尺度上的γ射线通量变异性。我们的样本由1120个大麻，其中481个是扁平频谱无线电类星体（FSRQ），而639是BL LAC对象（BL LACS）。从2008年8月至2017年12月，我们的样本每月生成了样本的每月binned Light曲线，并通过使用过剩方差（F_VAR）量化可变性。在类似月的时间尺度上，371/481 FSRQ是可变的（80％），而BL LAC只有大约50％（304/639）的可变。这表明FSRQ比BL LAC对象更可变。对于FSRQ和BL LAC，我们发现平均F_VAR为0.55 +/- 0.33和0.47 +/- 0.29。 FSRQ中的大型F_VAR也可以通过对整体结构函数的分析确认。通过基于同步子在其宽带光谱能量分布中峰的位置将我们的大麻样本划分，我们发现低同步器（LSP）源的低同步器的平均F_VAR值为0.54 +/- 0.32，而中间同步峰（ISP）峰值（ISP）峰值（HSSP）peactron +0.-HSP峰值 +/hsp-5的peacte +/hsschrotrotron pread 0.-f _ var +five 0.-hsp pread 0.-hsp的peactron +/f ive/hsspem pread 0.-hsp pread 0 0.分别为0.47 +/- 0.33。在月份的时间尺度上，我们发现FSRQ相对于BL LACS显示出高度66％的可变性周期（DC），而DC为36％。我们发现，f_var和变异性的时间尺度（τ）都与黑洞质量无关。我们注意到，发现F_VAR与多普勒因子（δ）弱相关，并且τ与δ也弱相关。我们样本中的大多数来源都具有几天的τ，这可能与喷气机中的过程有关。我们发现FSRQ和BL LAC之间τ的分布的边际差异。
We used the data from the Fermi Gamma-ray Space Telescope to characterise the γ-ray flux variability of blazars on month-like time scales. Our sample consists of 1120 blazars of which 481 are flat spectrum radio quasars (FSRQs) and 639 are BL Lac objects (BL Lacs). We generated monthly binned light curves of our sample for a period of approximately nine years from 2008 August to 2017 December and quantified variability by using excess variance (F_var). On month-like time scales, 371/481 FSRQs are variable ( 80%), while only about 50% (304/639) of BL Lacs are variable. This suggests that FSRQs are more variable than BL Lac objects. We find a mean F_var of 0.55 +/- 0.33 and 0.47 +/- 0.29 for FSRQs and BL Lacs respectively. Large F_var in FSRQs is also confirmed from the analysis of the ensemble structure function. By Dividing our sample of blazars based on the position of the synchrotron peak in their broad-band spectral energy distribution, we find that the low synchrotron peaked (LSP) sources have the largest mean F_var value of 0.54 +/- 0.32 while the intermediate synchrotron peaked (ISP) and high synchrotron peaked (HSP) sources have mean F_var values of 0.45 +/- 0.25 and 0.47 +/- 0.33 respectively. On month-like time scales, we find FSRQs to show a high duty cycle (DC) of variability of 66% relative to BL Lacs that show a DC of 36%. We find that both the F_var and time scale of variability (τ) do not correlate with the black hole mass. We note that F_var is found to be weakly correlated with Doppler factor (δ) and τ is also weakly correlated with δ. Most of the sources in our sample have τ of the order of days, which might be related to processes in the jet. We find marginal difference in the distribution of τ between FSRQs and BL Lacs.
