We present the results of the γ-ray flux distribution study on the brightest blazars which were observed by Fermi-LAT. We selected 50 of the brightest blazars based on the maximum number of detections reported in the...We present the results of the γ-ray flux distribution study on the brightest blazars which were observed by Fermi-LAT. We selected 50 of the brightest blazars based on the maximum number of detections reported in the Third LAT AGN Catalog. We performed standard unbinned maximum likelihood analysis on the LAT data during the period between August 2008 and December 2016, in order to obtain the average monthly flux. After quality cuts, blazars for which at least 90% of the total flux had survived were selected for further study, and this included 19 FSRQs and 19 BL Lacs. The Anderson-Darling and χ2 tests suggest that the integrated monthly flux follows a log-normal distribution for all sources, except for three FSRQs for which neither a normal nor a log-normal distribution was preferred. A double log-normal flux distribution tendency was observed in these sources, though this has to be confirmed with improved statistics. We also found that the standard deviation of the log-normal flux distribution increases with the mean spectral index of the blazar, and can be fitted with a line of slope 0.24±0.04. We repeat our study on three additional brightest unclassified blazars to identify their flux distribution properties. Based on the features of their log-normal flux distribution, we infer these unclassified blazars may be closely associated with FSRQs. We also highlight that considering the lognormal behavior of the flux distribution of blazars, averaging their long term flux on a linear scale can largely underestimate the nominal flux and this discrepancy can propagate down to the estimation of source parameters through spectral modeling.展开更多
The correlations between broad-line emission,polarization,and core-dominance parameters are investigated for a sample of 148 blazars(BL Lacertae objects-BLs and flat spectrum radio quasars-FSRQs). An anti-correlation ...The correlations between broad-line emission,polarization,and core-dominance parameters are investigated for a sample of 148 blazars(BL Lacertae objects-BLs and flat spectrum radio quasars-FSRQs). An anti-correlation between the broad-line luminosity and the linear polarization is found. The broad-line and polarization relation can be explained by using a relativistic beaming model,which perhaps suggests that BL Lacs and FSRQs are a single class. We also investigated the relation between the ratio of the broad-line luminosity to the Eddington luminosity and linear polarization,and that between the ratio of the broad-line luminosity to the Eddington luminosity and the core-dominance parameter.展开更多
利用支持向量机(Support Vector Machine,SVM)、随机森林(Random Forest,RF)、集成学习(Ensemble Learning,EM)和多层感知机(Multi-Layer Perceptron,MLP)将罗马5期耀变体多波段目录(The 5th edition of the Roma-BZCAT Multifrequency ...利用支持向量机(Support Vector Machine,SVM)、随机森林(Random Forest,RF)、集成学习(Ensemble Learning,EM)和多层感知机(Multi-Layer Perceptron,MLP)将罗马5期耀变体多波段目录(The 5th edition of the Roma-BZCAT Multifrequency Catalogue of Blazars,5BZCAT)中227个不确定类型的耀变体(Blazars of Uncertain type,BZUs)分为蝎虎天体候选体和平谱射电类星体候选体,并通过特征工程和网格搜索方法提高分类准确率。综合4种分类器的分类结果,将判别概率阈值设为0.8,得到33个蝎虎天体候选体和119个平谱射电类星体候选体。展开更多
基金the Indian Space Research Organization program(ISRO-RESPOND)for the financial support(Grant No.ISRO/RES/2/396)
文摘We present the results of the γ-ray flux distribution study on the brightest blazars which were observed by Fermi-LAT. We selected 50 of the brightest blazars based on the maximum number of detections reported in the Third LAT AGN Catalog. We performed standard unbinned maximum likelihood analysis on the LAT data during the period between August 2008 and December 2016, in order to obtain the average monthly flux. After quality cuts, blazars for which at least 90% of the total flux had survived were selected for further study, and this included 19 FSRQs and 19 BL Lacs. The Anderson-Darling and χ2 tests suggest that the integrated monthly flux follows a log-normal distribution for all sources, except for three FSRQs for which neither a normal nor a log-normal distribution was preferred. A double log-normal flux distribution tendency was observed in these sources, though this has to be confirmed with improved statistics. We also found that the standard deviation of the log-normal flux distribution increases with the mean spectral index of the blazar, and can be fitted with a line of slope 0.24±0.04. We repeat our study on three additional brightest unclassified blazars to identify their flux distribution properties. Based on the features of their log-normal flux distribution, we infer these unclassified blazars may be closely associated with FSRQs. We also highlight that considering the lognormal behavior of the flux distribution of blazars, averaging their long term flux on a linear scale can largely underestimate the nominal flux and this discrepancy can propagate down to the estimation of source parameters through spectral modeling.
基金was partially supported by the National Natural Science Foundation of China (Grant Nos. 10573005 and 10633010)the National Basic Research Program of China (Grant No. 2007CB815405)the Fund of the 11th Five-year Plan for Key Construction Academic Subject (Optics) of Hunan Province
文摘The correlations between broad-line emission,polarization,and core-dominance parameters are investigated for a sample of 148 blazars(BL Lacertae objects-BLs and flat spectrum radio quasars-FSRQs). An anti-correlation between the broad-line luminosity and the linear polarization is found. The broad-line and polarization relation can be explained by using a relativistic beaming model,which perhaps suggests that BL Lacs and FSRQs are a single class. We also investigated the relation between the ratio of the broad-line luminosity to the Eddington luminosity and linear polarization,and that between the ratio of the broad-line luminosity to the Eddington luminosity and the core-dominance parameter.
文摘利用支持向量机(Support Vector Machine,SVM)、随机森林(Random Forest,RF)、集成学习(Ensemble Learning,EM)和多层感知机(Multi-Layer Perceptron,MLP)将罗马5期耀变体多波段目录(The 5th edition of the Roma-BZCAT Multifrequency Catalogue of Blazars,5BZCAT)中227个不确定类型的耀变体(Blazars of Uncertain type,BZUs)分为蝎虎天体候选体和平谱射电类星体候选体,并通过特征工程和网格搜索方法提高分类准确率。综合4种分类器的分类结果,将判别概率阈值设为0.8,得到33个蝎虎天体候选体和119个平谱射电类星体候选体。
