The gamma-ray spectral index changes for blazars

作     者：YANG JiangHe FAN JunHui NIE JianJun YANG RuShu 

作者机构：Department of Physics and Electronics ScienceHunan University of Arts and ScienceChangde 415000China Center for AstrophysicsGuangzhou UniversityGuangzhou 510405China 

出 版 物：《Science China(Physics,Mechanics & Astronomy)》 (中国科学：物理学、力学、天文学（英文版）)

年 卷 期：2012年第55卷第11期

页      面：2179-2185页

核心收录：

学科分类：07[理学] 070401[理学-天体物理] 0704[理学-天文学] 0713[理学-生态学] 

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) 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 

主　　题：active galactic nuclei (AGN) blazars gamma-ray emission spectral index 

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.