GAMMA-RAY LIGHT CURVES AND VARIABILITY OF BRIGHT FERMI-DETECTED BLAZARS
GAMMA-RAY LIGHT CURVES AND VARIABILITY OF BRIGHT FERMI-DETECTED BLAZARS
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DOI：
10.1088/0004-637x/722/1/520
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发表时间：
2010-04
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影响因子：
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通讯作者：
A. Abdo;M. Ackermann;M. Ajello;E. Antolini;L. Baldini;J. Ballet;G. Barbiellini;D. Bastieri
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文献类型：
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作者：
A. Abdo;M. Ackermann;M. Ajello;E. Antolini;L. Baldini;J. Ballet;G. Barbiellini;D. Bastieri
本文介绍了高置信度费米大天区望远镜明亮活动星系核样本（LBAS）中106个天体的光变曲线以及首次系统表征的变化。每周光变曲线的样品，在前11个月的费米调查（2008年8月4日至2009年7月4日），进行了测试的可变性和他们的属性进行量化，通过自相关函数和结构函数分析。对于最亮的源，提取3或4天的分箱光变曲线，以确定功率密度谱（PDS），并拟合主要耀斑的时间结构。超过50%的源被发现是具有高显著性的变量，其中高状态不超过总观测范围的1/4。平坦谱射电类星体和低/中同步加速器频率峰值BL Lac对象的变化幅度较大。从每周光变曲线得出的自相关时间尺度从4周到12周不等。样品的可变源具有每周和3-4天的面元光变曲线，可以用1/fα PDS描述，并显示出两种伽马射线变化：（1）相当恒定的基线，具有零星的耀斑活动，其特征是较平坦的PDS斜率，类似于偶尔闪烁的闪烁和红噪声;（2）-对少数耀变体进行测量，显示出强烈的活动-复杂和结构化的时间轮廓，其特征是长-长期记忆和陡峭的PDS斜率，反映了随机游走的基本机制。最亮的22个FSRQ和6个最亮BL拉克的PDS的平均斜率分别为1.5和1.7。对在10个最亮的LBAS源中观测到的分辨良好的耀斑的时间剖面的研究表明，它们一般具有对称的剖面，它们的总持续时间在10至100天之间。本文的结果可以帮助对未知源的源类识别，并可以作为更详细的分析最亮的伽玛射线耀变体的参考。
This paper presents light curves as well as the first systematic characterization of variability of the 106 objects in the high-confidence Fermi Large Area Telescope Bright AGN Sample (LBAS). Weekly light curves of this sample, obtained during the first 11 months of the Fermi survey (2008 August 4–2009 July 4), are tested for variability and their properties are quantified through autocorrelation function and structure function analysis. For the brightest sources, 3 or 4 day binned light curves are extracted in order to determine power density spectra (PDSs) and to fit the temporal structure of major flares. More than 50% of the sources are found to be variable with high significance, where high states do not exceed 1/4 of the total observation range. Variation amplitudes are larger for flat spectrum radio quasars and low/intermediate synchrotron frequency peaked BL Lac objects. Autocorrelation timescales derived from weekly light curves vary from four to a dozen of weeks. Variable sources of the sample have weekly and 3–4 day bin light curves that can be described by 1/fα PDS, and show two kinds of gamma-ray variability: (1) rather constant baseline with sporadic flaring activity characterized by flatter PDS slopes resembling flickering and red noise with occasional intermittence and (2)—measured for a few blazars showing strong activity—complex and structured temporal profiles characterized by long-term memory and steeper PDS slopes, reflecting a random walk underlying mechanism. The average slope of the PDS of the brightest 22 FSRQs and of the 6 brightest BL Lacs is 1.5 and 1.7, respectively. The study of temporal profiles of well-resolved flares observed in the 10 brightest LBAS sources shows that they generally have symmetric profiles and that their total duration vary between 10 and 100 days. Results presented here can assist in source class recognition for unidentified sources and can serve as reference for more detailed analysis of the brightest gamma-ray blazars.