• J. J. Nie

      Articles written in Journal of Astrophysics and Astronomy

    • Dependence of Core and Extended Flux on Core Dominance Parameter for Radio Sources

      J. J. Nie J. H. Yang

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      Based on two extragalactic radio source samples, the core dominance parameter is calculated, and the correlations between the core/extended flux density and core dominance parameter are investigated. When the core dominance parameter is lower than unity, it is linearly correlated with the core flux density, but it is not correlated with the extended flux density. When the core dominance parameter is higher than unity, it is not correlated with the core flux density, but it is linearly correlated with the extended flux density. Therefore, there are different results from different samples. The results can be explained using a relativistic beaming model.

    • Spectral Index Changes with Brightness for 𝛾-Ray Loud Blazars

      J. H. Yang R. S. Yang J. J. Nie J. H. Fan

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      Based on Fermi 1FGL and 2FGL data, a sample of 572 𝛾-ray loud blazars are selected, in which each source has both 𝛾-ray flux and spectral index in 1FGL and 2FGL, respectively. Theoretic relation of spectral index changes depending on 𝛾-ray brightness is obtained. The correlations between the ratio of 𝛾-ray flux densities and the differences of the 𝛾-ray spectral indices are discussed for the three subclasses of HBL, LBL and FSRQs. Results show that the ratio is related with the differences for the three subclasses. It is consistent with the theoretical result and it indicates that the spectrum becomes flat as the source brightens in the 𝛾-ray band.

    • Effective Spectral Indices of Core and Extended Emissions for Radio Sources

      R. S. Yang J. H. Yang J. J. Nie

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      From some available literatures, a sample of 393 radio sources is selected. The core and extended spectral indices are calculated. Results show that the core spectral index is different from the extended spectral index with the middle values approximately being 0 and 0.8 respectively.

    • Relation of Core Dominance Parameter and Extended Spectral Index for Radio Sources

      J. H. Yang J. J. Nie J. H. Fan

      More Details Abstract Fulltext PDF

      The correlations between differences of two core dominance parameters and core/extended spectral index are investigated. The extended spectral index is associated with the differences very well, while there is a weak relationship between core spectral index and the differences. The average core spectral index tends to be a `constant’ ∼ 0.0.

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    • Continuous Article Publication

      Posted on January 27, 2016

      Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

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