Multiwaveband polarimetric observations of NRAO 530 on parsec-scale
Multiwaveband polarimetric observations of NRAO 530 on parsec-scale
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NRAO 530 秒差距尺度的多波段偏振观测
DOI：
10.1111/j.1365-2966.2010.17193.x
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发表时间：
2010-06
影响因子：
4.8
通讯作者：
Shen ZQ
中科院分区：
文献类型：
--
作者：
Chen YJ;Shen ZQ
我们报告甚长基线阵列极化观测NRAO 530在5，8，15，22和43 GHz期间在1997年2月的一个星期。我们提出了在所有这些频率的总强度，分数偏振和电矢量位置角（EVPA）的分布。对全偏振能见度数据进行了模型拟合。由此，与主通量中心分量B相比，拟合的最南分量A被确认为射电结构的核心，具有较高的亮温和15 ~ 43 GHz的硬谱。分量A的相对高的偏振度可能源于其复杂的无线电结构，其可以在86 GHz处解析。相比之下，组分B显示出很好拟合的幂律光谱，光谱指数约为-0.5（f α V（α）），EVPA和波长平方之间呈线性相关，观察到的旋转测量值约为-1062 rad m（2），表明其结构单一。假设分量B在这些频率下具有可比较的偏振度而没有去偏振，则分数偏振随波长的减小主要是由不透明度和法拉第旋转引起的，其中不透明度起着相当大的作用。在5 GHz和8 GHz下，探测到了一个部分极化的脊鞘状结构，几乎覆盖了整个发射区，沿射流脊沿着方向极化度相对较低，朝向射流两侧极化度逐渐变高。在5 GHz的线性偏振显示了三个独立的偏振发射区域，交替对齐和正交的偏振矢量向下喷射。极化在顶部两个区域之间变为零，最高极化水平出现在顶部和底部。5-和8-GHz的图像显示了EVPA在射流宽度上的变化以及沿着射流的变化。这些复杂的偏振特性可以用大螺旋磁场的存在或沿喷流压缩和剪切的缠结磁场来解释。这些可以进一步确定的多频偏振甚长基线干涉测量观测具有足够高的分辨率和灵敏度跨越适当的频率范围。
We report on Very Long Baseline Array polarimetric observations of NRAO 530 at 5, 8, 15, 22 and 43 GHz made during one week in 1997 February. We present the total intensity, the fractional polarization and the electric vector position angle (EVPA) distributions at all these frequencies. A model fitting has been performed to the full polarization visibility data. From this, the fitted southernmost component A is confirmed as the core of the radio structure with relatively high brightness temperature and hard spectrum between 15 and 43 GHz in comparison with the central component B of dominant flux. The relatively high degree of polarization for the component A may arise from its complex radio structure, which can be resolved at 86 GHz. In contrast, the component B shows a well-fitted power-law spectrum with a spectral index of about-0.5 (f alpha V(alpha)), and a linear correlation between EVPAs andwavelength square with an observed rotation measure of about -1062 rad m(2), indicating its structural singleness. Assuming that the component B has a comparable degree of polarization without depolarization at these frequencies, the decrease in fractional polarization with wavelength mainly results from opacity and Faraday rotation, in which the opacity plays quite a large role. A spine-sheath-like structure in fractional polarization (m) is detected, covering almost the whole emission region at 5 and 8 GHz, with a degree of polarization relatively low along the jet spine, becoming higher towards two sides of the jet. The linear polarization at 5 GHz shows three separate polarized emission regions with alternately aligned and orthogonal polarization vectors down the jet. The polarization goes to zero between the top two regions, with the highest polarization level occurring at the top and bottom. The 5- and 8-GHz images show EVPA changes across the width of the jet as well as along the jet. These complex polarimetric properties can be explained in terms of either the presence of a large helical magnetic field or tangled magnetic fields compressed and sheared down the jet. These can be further determined by multifrequency polarimetric very long baseline interferometry observations with sufficient high resolution and sensitivity spanning an appropriate frequency range.
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DOI：
10.1086/431901
发表时间：
2005-05
期刊：
The Astrophysical Journal Letters
影响因子：
--
作者：
R. Zavala;G. Observatory;Nrao;Kavli Institute for Astrophysics;Cosmology
通讯作者：
R. Zavala;G. Observatory;Nrao;Kavli Institute for Astrophysics;Cosmology
DOI：
10.1088/0004-6256/147/6/143
发表时间：
2014-03
期刊：
The Astronomical Journal
影响因子：
--
作者：
T. Hovatta;M. Aller;H. Aller;E. Clausen-Brown;D. Homan;Y. Kovalev;M. Lister;A. Pushkarev;
通讯作者：
T. Hovatta;M. Aller;H. Aller;E. Clausen-Brown;D. Homan;Y. Kovalev;M. Lister;A. Pushkarev;
DOI：
10.1086/320858
发表时间：
2001-01
期刊：
The Astrophysical Journal Supplement Series
影响因子：
--
作者：
S. Jorstad;A. Marscher;J. Mattox;A. Wehrle;S. Bloom;A. V. Yurchenko
通讯作者：
S. Jorstad;A. Marscher;J. Mattox;A. Wehrle;S. Bloom;A. V. Yurchenko
DOI：
10.1046/j.1365-8711.2001.04147.x
发表时间：
2001-02
影响因子：
4.8
作者：
D. Gabuzda;J. Gómez
通讯作者：
D. Gabuzda;J. Gómez
影响因子：
1
作者：
A. Pushkarev
通讯作者：
A. Pushkarev