Based on the radio light curves in 22 GHz and 37 GHz from the Metsahovi monitoring program and the optical light curves in BVRI bands from previously published results and the"Whole Earth Blazar Telescope"(W...Based on the radio light curves in 22 GHz and 37 GHz from the Metsahovi monitoring program and the optical light curves in BVRI bands from previously published results and the"Whole Earth Blazar Telescope"(WEBT)archives,we analyze the time delay among 22 GHz,37 GHz and optical bands(B,V,R,I)of BL Lacertae by means of discrete correlation method.The results suggest there exist strong correlation among 22 GHz,37 GHz and optical bands(B,V,R,I)with zero-lag.The 37 GHz lags behind R band by 11 months.The correlation of brightness and color index among BVRI bands,brightness and spectral index between 37GHz and 22 GHz are also investigated.The results show a clear trend of bluer-when-brighter.展开更多
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 densiti...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.展开更多
基金supported by the LangFang Teacher’s College Research Programme of China(Grant No.LSZQ201103)LangFang Municipal Science and Technology Research and Development Program of China(Grant No.2012011002)Colleges and Universities in Hebei Province Science and Technology Research Project(Grant No.Z2013065)
文摘Based on the radio light curves in 22 GHz and 37 GHz from the Metsahovi monitoring program and the optical light curves in BVRI bands from previously published results and the"Whole Earth Blazar Telescope"(WEBT)archives,we analyze the time delay among 22 GHz,37 GHz and optical bands(B,V,R,I)of BL Lacertae by means of discrete correlation method.The results suggest there exist strong correlation among 22 GHz,37 GHz and optical bands(B,V,R,I)with zero-lag.The 37 GHz lags behind R band by 11 months.The correlation of brightness and color index among BVRI bands,brightness and spectral index between 37GHz and 22 GHz are also investigated.The results show a clear trend of bluer-when-brighter.
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)+5 种基金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
文摘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.
