The gamma-ray spectral index changes for blazars  

作　　者：YANG JiangHe FAN JunHui NIE JianJun YANG RuShu 

机构地区：[1]Department of Physics and Electronics Science,Hunan University of Arts and Science,Changde 415000,China [2]Center for Astrophysics,Guangzhou University,Guangzhou 510405,China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2012年第11期2179-2185,共7页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.10633010 and 11173009);the National Basic Research Program of China(Grant No.2007CB 815405);the Bureau of Education of Guangzhou Municipality(Grant No.11 Sui-Jiao-Ke[2009]);Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme (GDUPS)(2009);Yangcheng Scholar Funded Scheme(Grant No. 10A027S);Hunan Provincial Natural Science Foundation(Grant No. 10JJ3020);Fund of the 11th Five-year Plan for Key Construction Academic Subject(Optics) of Hunan Province,Research Funding from Hunan University of Arts and Science(Grant No.JJZD201101);the Guangzhou Education Bureau and Guangzhou Science and Technology Bureau

摘　　要：Based upon Fermi 1FGL and EGRET 3EG samples, a sample including 79 blazars （53 FSRQs, 26 BL Lacs） is presented. It is investigated that the correlations between the ratio of EGRET to Fermi blazars g-ray flux densities and the spectral index differ for EGRET to Fermi blazars for three subclasses of high-frequency peaked BL Lacertae objects-HBL, low-frequency peaked BL Lacertae objects-LBL, and flat spectrum radio quasars-FSRQs. There is a consistent relationship between the ratio of the two γ-ray flux densities and the spectral index difference for the three subclasses. It suggests that the spectrum changed with the source brightness in the gamma-ray band. Both the spectral index difference and the correlation slopes follow a continuous sequence from FSRQs to LBLs to HBLs, which is consistent with the noted blazar sequence.Based upon Fermi 1FGL and EGRET 3EG samples,a sample including 79 blazars(53 FSRQs,26 BL Lacs) is presented.It is investigated that the correlations between the ratio of EGRET to Fermi blazars-ray flux densities and the spectral index differ for EGRET to Fermi blazars for three subclasses of high-frequency peaked BL Lacertae objects-HBL,low-frequency peaked BL Lacertae objects-LBL,and flat spectrum radio quasars-FSRQs.There is a consistent relationship between the ratio of the two γ-ray flux densities and the spectral index difference for the three subclasses.It suggests that the spectrum changed with the source brightness in the gamma-ray band.Both the spectral index difference and the correlation slopes follow a continuous sequence from FSRQs to LBLs to HBLs,which is consistent with the noted blazar sequence.

关 键 词：active galactic nuclei （AGN） BLAZARS gamma-ray emission spectral index 

分 类 号：P157.7[天文地球—天文学] S812.8[农业科学—草业科学]