How Fast Are The Large-Scale Jets In Quasars?
How Fast Are The Large-Scale Jets In Quasars?
复制标题
类星体中的大型喷流有多快？
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
S. Aaron
中科院分区：
文献类型：
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作者：
J. Wardle;S. Aaron
我们分析了从 Bridle 等人制作的 13 个 3CR 类星体的深 VLA 图像中测量到的射流与反射流通量比，以便得出对多普勒增强程度（以及千秒差距尺度上的特征射流速度）以及允许射流和反射流之间有多少内在不对称性的约束。主要结果是 Bridle 等人测量的大射流-反射流亮度比。必须几乎完全归因于多普勒效应，需要特征喷射速度？千秒差距尺度上的 0.6c。允许适度的内在不对称，但不会显着降低特征速度，而 VLBI 数据则排除大的不对称。数据还要求排除靠近天空平面的方向（e max < 75°），因此至少有一些类星体伪装成星系。对于 45° 至 60° 范围内的 e max，如某些统一方案中所建议的，最佳拟合喷射速度在 0.6c 至 0.7c 范围内。对 3CR 类星体完整样本的喷流与洛贝比的分析得出喷流速度的上限 < 0.95c，这表明秒差距和千秒差距尺度之间至少存在一定的减速。
We analyse the jet-to-counterjet flux ratios measured from deep VLA images of 13 3CR quasars made by Bridle et aI., in order to derive constraints on the degree of Doppler boosting (and hence the characteristic jet speeds on kiloparsec scales) and on how much intrinsic asymmetry between jets and counterjets is permitted. The main result is that the large jet-counterjet brightness ratios measured by Bridle et al. must be attributed almost entirely to the Doppler effect, requiring characteristic jet speeds ? 0.6c on kiloparsec scales. Modest intrinsic asymmetries are permitted, but do not reduce the characteristic speed significantly, while large asymmetries are ruled out by VLBI data. The data also require that orientations close to the plane of the sky are excluded (e max < 75°), so at least some quasars masquerade as galaxies. For e max in the range 45° to 60°, as suggested in certain unified schemes, the best fitting jet speeds are in the range 0.6c to 0.7c. Analysis of jet-to-Iobe ratios for a complete sample of 3CR quasars leads to an upper limit on jet speed of < 0.95c, demonstrating that there is at least some deceleration between parsec and kiloparsec scales.