Multiepoch Very Long Baseline Array Observations of EGRET-detected Quasars and BL Lacertae Objects: Superluminal Motion of Gamma-Ray Bright Blazars
Multiepoch Very Long Baseline Array Observations of EGRET-detected Quasars and BL Lacertae Objects: Superluminal Motion of Gamma-Ray Bright Blazars
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DOI：
10.1086/320858
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发表时间：
2001-01
期刊：
影响因子：
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通讯作者：
S. Jorstad;A. Marscher;J. Mattox;A. Wehrle;S. Bloom;A. V. Yurchenko
中科院分区：
文献类型：
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作者：
S. Jorstad;A. Marscher;J. Mattox;A. Wehrle;S. Bloom;A. V. Yurchenko
本文介绍了1993年11月至1997年7月期间利用甚长基线射电望远镜阵（VLBA）在43、22、偶尔15和8.4GHz上对42个亮耀变体（31个类星体和11个BL Lac天体）射电辐射结构的监测结果。我们测定了33个射电源的自行，发现γ射电源的视超光速运动比一般明亮致密射电源的视超光速运动快得多。这是由于γ射线通量对外部辐射康普顿和同步辐射自康普顿辐射的相对论射束水平的强烈依赖性。VLBI核的通量密度与γ射线通量之间存在正相关（相关系数r = 0.45），γ射线视光度与喷流分量的超光速之间存在中等相关（偏相关系数r = 0.31），这与γ射线发射起源于相对论喷流的一个非常致密的区域并且是高度成束的情况是一致的。在43%的源中，喷流在秒差距尺度上弯曲超过20°，这与位置角的适度实际变化的投影效应的放大一致。在样本中的27个源中，至少有一个非核心分量在我们的观测期间似乎是静止的。不同的特点，固定功能接近和远离核心导致我们建议两个不同类别的固定组件：那些在约2质量的核心，可能与站立的流体动力学压缩，和那些更远的射流，这往往是与弯曲的射流。
We present the results of a program to monitor the structure of the radio emission in 42 γ-ray bright blazars (31 quasars and 11 BL Lac objects) with the Very Long Baseline Array (VLBA) at 43, 22, and occasionally 15 and 8.4 GHz, over the period from 1993 November to 1997 July. We determine proper motions in 33 sources and find that the apparent superluminal motions in γ-ray sources are much faster than for the general population of bright compact radio sources. This follows the strong dependence of the γ-ray flux on the level of relativistic beaming for both external radiation Compton and synchrotron self-Compton emission. There is a positive correlation (correlation coefficient r = 0.45) between the flux density of the VLBI core and the γ-ray flux and a moderate correlation (partial correlation coefficient r = 0.31) between γ-ray apparent luminosity and superluminal velocities of jet components, as expected if the γ-ray emission originates in a very compact region of the relativistic jet and is highly beamed. In 43% of the sources the jet bends by more than 20° on parsec scales, which is consistent with amplification by projection effects of modest actual changes in position angle. In 27 of the sources in the sample there is at least one non-core component that appears to be stationary during our observations. Different characteristics of stationary features close to and farther from the core lead us to suggest two different classes of stationary components: those within about 2 mas of the core, probably associated with standing hydrodynamical compressions, and those farther down the jet, which tend to be associated with bends in the jet.