The relationship between the radio core dominance parameter and the spectral index in different classes of extragalactic radio sources
The relationship between the radio core dominance parameter and the spectral index in different classes of extragalactic radio sources
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不同类别河外射电源的射电核心优势参数与频谱指数的关系
DOI：
10.1088/1674-4527/11/12/004
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
华同旭
中科院分区：
文献类型：
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作者：
樊军辉;杨江河;潘静;华同旭
活动星系核（AGN）有两大类，即射电噪AGN和射电静AGN。一个小的射电活动星系核子集被称为耀变体，它显示出极端的观测特性，如快速变化，高光度，高和可变的偏振和超光速运动。所有这些观测特性可能是由于相对论性的光束效应，射流指向接近视线。观察结果表明，取向可以用核心优势参数R来表示。在某种程度上，R与聚束效应有关。耀变体被认为与Fanaroff & Riley I/II型（FRI/II）射电星系统一。本文收集了1223个活动星系核的相关观测资料，其中包括77个BL Lacertae天体、495个类星体、460个星系、119个FR和72个未知源，计算了它们的核优势参数和光谱指数，讨论了它们之间的关系，并进行了讨论。我们的分析表明，BL Lacertae天体的核心优势参数大于类星体和星系，BL Lacertae天体的射电光谱指数低于类星体和星系。我们还发现，核心优势参数光谱指数相关性存在的一个大的样本，这可能来自于相对论性的聚束效应。
Active galactic nuclei (AGNs) have two major classes, namely radio loud AGNs and radio quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which display extreme observational properties, such as rapid variability, high luminosity, high and variable polarization, and superluminal motion. All of those observational properties are probably due to a relativistic beaming effect with the jet pointing close to the line of sight. Observations suggest that the orientation can be expressed by a core-dominance parameter, R. The R, to some extent, is associated with the beaming effect. Blazars are believed to be unified with Fanaroff & Riley type I/II (FRI/II) radio galaxies. In this work, we collected relevant observations from the literature for a sample of 1223 AGNs including 77 BL Lacertae objects, 495 quasars, 460 galaxies, 119 FRs and 72 unidentified sources, and calculated the core-dominance parameters and spectral indexes, discussed the relationship between the two parameters, and gave some discussions. Our analysis suggests that the core-dominance parameters in BL Lacertae objects are larger than those in quasars and galaxies, and the radio spectral indexes in BL Lacertae objects are lower than those in quasars and galaxies. We also found that the core-dominance parameter-spectral index correlation exists for a large sample presented in this work, which may come from a relativistic beaming effect.