致密射电源0400+258的毫角秒尺度偏振研究

VLBI polarization study of compact radio sources 0400+258

利用美国甚长基线干涉阵,对致密射电源0400+258进行5 GHz和8 GHz双频段偏振观测,获得毫角秒尺度的辐射强度分布图像,并首次得到这个射电源在5 GHz和8 GHz频段的偏振矢量分布结果。源0400+258呈现单侧核—喷流结构,偏振辐射集中在射电核附近。通过4个频率的偏振分布,首次获得该源毫角秒尺度的旋转量分布。移除介质的影响后,得到该源内禀磁场结构,磁场方向大致沿着喷流方向。

Using the very long baseline array,we perform the double-band polarization observations of the compact radio source 0400+258 at 5 GHz and 8 GHz.We present its mas-resolution total intensity maps and,for the first time,its polarization maps at 5 GHz and 8 GHz frequency bands.The source 0400+258 displays one-sided core-jet structure,and the polarization emission is firmly detected in a region near the core.Besides,by fitting the polarization maps at four frequencies,the mas-scale rotation measure of the source is obtained for the first time.After removing the rotation measure,the intrinsic magnetic field of the source is acquired,which demonstrates that the magnetic field direction is roughly parallel to the direction of the jet.