The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST) provides an increase in sensitivity and has detected rapid variability of gamma-ray sources.The variability time scales detected f...The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST) provides an increase in sensitivity and has detected rapid variability of gamma-ray sources.The variability time scales detected from the gamma-ray loud blazars by LAT and EGRET,and gamma-ray luminosity are used to estimate the central black hole masses.In this work,we find that the lower limits of central black hole masses are in a range of (0.3-24)×107M⊙,which are compared with those obtained by other authors.Our results are consistent with other authors' results.Also,the Lorentz factor,Γ,and the propagation angle,θ,are obtained for 18 blazars for which superluminal motions are known.展开更多
Evidence for the long-term optical curve variability and colour behaviour of the BL Lac object Mkn 421 is presented. Our results show that the amplitude of the optical variations of Mkn 421 is only about △B=4.7 magni...Evidence for the long-term optical curve variability and colour behaviour of the BL Lac object Mkn 421 is presented. Our results show that the amplitude of the optical variations of Mkn 421 is only about △B=4.7 magnitude in the B-band for its photometric history from 1899 to 2002. The results of optical photometric monitoring of the Mkn 421 from April 2000 to Jan 2002 are provided. During our observation, Mkn 421 shows significant rapid variations and exhibits short time variability of 2.42 hours in the B band. A strong correlation between the B - V colour index and the magnitude in the B band is found. Our charge coupled device （CCD） photometry of Mkn 421 shows that the measured results are in good agreement with the predicted optical variability period of about 23 years.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10573005 and 10633010)the National Basic Research Program of China (Grant No. 2007CB815405)+1 种基金Hunan Provincial Natural Science Foundation of China (Grant No. 10JJ3020)the Fund of the 11th Five-year Plan for Key Construction Academic Subject (Optics) of Hunan Province
文摘The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope (formerly GLAST) provides an increase in sensitivity and has detected rapid variability of gamma-ray sources.The variability time scales detected from the gamma-ray loud blazars by LAT and EGRET,and gamma-ray luminosity are used to estimate the central black hole masses.In this work,we find that the lower limits of central black hole masses are in a range of (0.3-24)×107M⊙,which are compared with those obtained by other authors.Our results are consistent with other authors' results.Also,the Lorentz factor,Γ,and the propagation angle,θ,are obtained for 18 blazars for which superluminal motions are known.
基金Project supported by an CRCG grant of the University of Hong Kong, Yunnan Provincial Foundation of Science of China （Grant No 2004A0027M） and the National Natural Science Foundation of China（Grant No 10363002）, and the Natural Science Foundation of China Education Department（Grant No 02142）.
文摘Evidence for the long-term optical curve variability and colour behaviour of the BL Lac object Mkn 421 is presented. Our results show that the amplitude of the optical variations of Mkn 421 is only about △B=4.7 magnitude in the B-band for its photometric history from 1899 to 2002. The results of optical photometric monitoring of the Mkn 421 from April 2000 to Jan 2002 are provided. During our observation, Mkn 421 shows significant rapid variations and exhibits short time variability of 2.42 hours in the B band. A strong correlation between the B - V colour index and the magnitude in the B band is found. Our charge coupled device （CCD） photometry of Mkn 421 shows that the measured results are in good agreement with the predicted optical variability period of about 23 years.
