排序方式： 共有4条查询结果，搜索用时 78 毫秒
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Shao-Hua Zhang Hui-Yuan Wang Hong-Yan Zhou Ting-Gui Wang Peng Jiang Key Laboratory for Researches in Galaxies Cosmology 《中国天文和天体物理学报》2011,(10)
We report the discovery of a broad absorption line (BAL) of ～ 104 km s-1 in width in the previously known BL Lac object PKS 0138-097, which we tentatively identified as an Mg II BAL. This is the first detection of a BAL, which is sometimes seen in powerful quasars with high accretion rates, in a BL Lac object. The BAL was clearly detected in its spectra spanning two epochs at a high luminosity state taken in the Sloan Digital Sky Survey (SDSS), while it disappeared in three SDSS spectra taken at a low lumin... 相似文献
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A computational code is developed to help identify metal absorption linesin high resolution QSO spectra,especially in the Lyα forest.The input to the codeincludes a list of line central wavelengths,column densities and Doppler widths.Thecode then searches for candidate metal absorption systems and assesses the probability that each system could be real.The framework of the strategy we employ isdescribed in detail and we discuss how to estimate the errors in line profile fitting thatare essential to identifi... 相似文献
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Jing Tang Wen-Fei Yu Zhen Yan Key Laboratory for Research in Galaxies Cosmology Shanghai Astronomical Observatory Shanghai China 《中国天文和天体物理学报》2011,(4)
We have studied X-ray spectral state transitions that can be seen in the longterm monitoring light curves of bright X-ray binaries from the All-Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE) and the Burst Alert Telescope (BAT) onboard Swift during a period of five years from 2005 to 2010.We have applied a program to automatically identify the hard-to-soft (H-S) spectral state transitions in the bright X-ray binaries monitored by the ASM and the BAT.In total,we identified 128 hard-to-soft t... 相似文献
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Fan Li Xin-Wu Cao Key Laboratory for Research in Galaxies Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai China Graduate University of Chinese Academy of Sciences Beijing China 《中国天文和天体物理学报》2011,(8)
A tight correlation between γ-ray and radio emission is found for a sample of BL Lacertae(BL Lac) objects detected by the Fermi Gamma-ray Space Telescope(Fermi) and the Energetic Gamma-Ray Experiment Telescope(EGRET) . The γ-ray emission of BL Lac objects exhibits strong variability,and the detection rate of γ-ray BL Lac objects is low,which may be related to the γ-ray duty cycle of BL Lac objects. We estimate the γ-ray duty cycle,δγ 0.11,for BL Lac objects detected by EGRET and Fermi. Using the empirical r... 相似文献
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