Fermi耀变体的γ射线多波段辐射与射电辐射的关系

The Correlations between Radio and γ-ray Emissions in Multi-bands for Fermi Blazars

从Fermi 3期源表(3FGL)中选择了一个含935个耀变体(blazar)的样本,包括415个平谱射电源(Flat Spectrum Radio Quasar, FSRQ), 520个蝎虎天体(BL Lac object, BL Lac),其中高同步峰BL Lac (HBL) 233个,中同步峰BL Lac (IBL) 144个,低同步峰BL Lac (LBL) 143个.研究了总样本、FSRQ、BL Lac及其子类HBL、LBL的射电1.4 GHz与γ射线在0.1、0.3、1、3、10 GeV处辐射流量密度的关系.结果显示:所有样本的射电1.4 GHz与5个波段γ射线的辐射流量都有强相关,相关系数在0.48–0.81之间,机会概率均小于10^(-4);对于不同的样本相关系数随着γ射线辐射频率的变化有不同的变化趋势,所有样本在5个波段的相关系数平均值随γ射线频率的增加而减小.该结果暗示,随着频率的升高, blazar的γ射线辐射主导机制在发生变化,在相同频率处,不同类型天体的辐射主导机制存在差异;HBL的γ射线辐射主要由同步自康普顿主导,而LBL的其他成份比HBL的更复杂;FSRQ的γ射线起源较BL Lac的复杂.

A sample including 935 blazars with 415 Flat Spectrum Radio Quasars(FSRQs)and 520 BL Lac objects(BL Lacs)(233 HBLs(High synchrotron peak frequency BL Lacs),144 IBLs(Intermediate synchrotron peak frequency BL Lacs),and 143 LBLs(Low synchrotron peak frequency BL Lacs))is selected in Fermi 3FGL catalogue.The correlations between two flux densities of the radio 1.4 GHz and γ-ray at 0.1,0.3,1,3,and 10 GeV are investigated for the samples of all blazars,FSRQs,BL Lacs,and subclasses of HBLs and LBLs,respectively.Results show that there are strong positive correlations between the two flux densities,with the correlation coefficients r=0.48–0.81 and the chance probabilities p all less than 10^-4;The correlation coefficient has different trends with the change of γ-ray emission frequency for different blazar samples,and the average correlation coefficients for all samples at the five respective bands decrease with the increase of γ-ray frequency.Therefore,with the increase of γ-ray frequency,the dominant mechanism of γ-ray radiation of blazar is changing,and at the same frequency the dominant mechanism is different for different samples.The γ-ray emission of HBLs may be mainly dominated by the synchrotron self-Compton,while the other mechanisms are responsible for the γ-ray emissions of LBLs.The origin of γ-ray in FSRQs is more complex than that of BL Lacs.