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201.
Zhi-Yuan Pei Jun-Hui Fan Denis Bastieri Utane Sawangwit Jiang-He Yang 《天文和天体物理学研究(英文版)》2019,(5):75-90
Active galactic nuclei(AGNs) can be divided into two major classes, namely radio-loud and radio-quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which are believed to be unified with Fanaroff-Riley type Ⅰ/Ⅱ(FRI/Ⅱ) radio galaxies. Following our previous work(Fan et al.), we present a sample of 2400 sources with measured radio flux densities of the core and extended components. The sample contains 250 BL Lacs, 520 quasars, 175 Seyferts, 1178 galaxies, 153 FRI or FRⅡ galaxies and 104 unidentified sources. We then calculate the radio core-dominance parameters and spectral indices, and study their relationship. Our analysis shows that the core-dominance parameters and spectral indices are quite different for different types of sources. We also confirm that the correlation between core-dominance parameter and spectral index exists for a large sample presented in this work. 相似文献
202.
Sky surveys represent one of the most important efforts to improve developments in astrophysics,especially when using new photometric bands. We are performing the Stellar Abundance and Galactic Evolution(SAGE) survey with a self-designed SAGE photometric system, which is composed of eight photometric bands. The project mainly aims to study the stellar atmospheric parameters of ~0.5 billion stars in ~12 000 deg2 of the northern sky, which mainly focuses on Galactic astronomy, as well as some aspects of extragalactic astronomy. This work introduces the detailed data reduction process of the test field NGC 6791, including the data reduction of single-exposure images and stacked multi-exposure images, and properties of the final catalog. 相似文献
203.
Pin-Song Zhao Hong Wu Cong Kevin Xu Ming Yang Fan Yang Yi-Nan Zhu Man I Lam Jun-Jie Jin Hai-Long Yuan Hao-Tong Zhang Shi-Yin Shen Jian-Rong Shi A-Li Luo Xue-Bing Wu Yong-Heng Zhao Yi-Peng Jing 《天文和天体物理学研究(英文版)》2019,(8)
We present optical luminosity functions(LFs) of galaxies in the~(0.1) g,~(0.1) r,~(0.1) i bands, calculated using data in~40 deg~2 sky area of the LAMOST Complete Spectroscopic Survey of Pointing Area(LaCoSSPAr) in the Southern Galactic Cap. Redshifts for galaxies brighter than r = 18.1 were obtained mainly with LAMOST. In each band, LFs derived using both parametric and non-parametric maximum likelihood methods agree well with each other. In the0.1 r band, our fitting parameters of the Schechter function are φ_*=(1.65 ± 0.36) × 10~(-2) h~3 Mpc~(-3), M_*=-20.69 ± 0.06 mag and α =-1.12 ± 0.08,which agree with previous studies. Separate LFs are also derived for emission line galaxies and absorption line galaxies. The LFs of absorption line galaxies show a dip at~(0.1) r ~18.5 and can be fitted well by a double-Gaussian function, suggesting a bimodality in passive galaxies. 相似文献
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提出一种使用非差非组合精密单点定位(PPP)估计和分析接收机DCB短时时变特征的方法。首先利用非差非组合PPP得到包含接收机DCB的重构电离层参数估值;然后通过IGS电离层GIMs格网模型内插剥离各历元站星斜向电离层距离延迟;最后通过最小二乘约束得到各历元接收机DCB解。由于格网本身精度(2~8 TECU)和插值精度限制,解算出来的接收机DCB并不能真实反映其短期时变特征。为此,提出利用站间单差或者历元间差分的方法还原其真实的变化态势。实验结果表明,所提出的方法能够正确估计接收机DCB,并能真实还原其短期时变特征,具有良好的适用性。 相似文献
207.
In this work, we collected a sample of 69 TeV blazars from TeVCat, obtained their multiwavelength observations, and fitted their spectral energy distributions by using a second degree polynomial function. The structure parameters of synchrotron bumps for 68 blazars and those of inverseCompton bumps for 56 blazars were derived. Then, we conducted statistical analysis on the parameters(curvature, peak frequency, peak luminosity, bolometric luminosity and X/γ-ray spectral indexes).From our analysis and discussions, we can conclude the following:(1) There is a clear positive correlation between the synchrotron peak frequency, log ν_p~s, and the inverse-Compton peak frequency, log ν_p~(IC),and between the synchrotron peak luminosity, log ν_p~sL_(νp)~s, and the inverse-Compton peak luminosity,log ν_p~(IC)L_(νp)~(IC).(2) The correlation between the peak frequency and the curvature of synchrotron bump is clearly different from that of the inverse-Compton bump, which further indicates that there are different emission mechanisms between them.(3) There is a correlation between log νIC pand γ-ray spectral index, α_γ, for the TeV blazars: log ν_p~(IC)=-(4.59 ± 0.30)α_γ+(32.67 ± 0.59), which is consistent with previous work.(4) An "L-shape" relation is found between log ν_p~s and α_X for both TeV blazars and Fermi blazars. A significant correlation between log νs pand X-ray photon index(α_X) is found for the TeV blazars with high synchrotron peak frequency: log ν_p~s=-(3.20 ± 0.34)α_X+(24.33 ± 0.79),while the correlation is positive for low synchrotron peaked TeV sources.(5) In the αX-αγdiagram,there is also an "L-shape." The anti-correlation is consistent with results available in the literature, and we also find a positive correlation between them.(6) Inverse-Compton dominant sources have luminous bolometric luminosities. 相似文献
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