论文标题
VLBA揭示了无线电中级类星体J2242+0334在z = 5.9
VLBA reveals the absence of a compact radio core in the radio intermediate quasar J2242+0334 at z =5.9
论文作者
论文摘要
高分辨率成像对于探索类星体中无线电发射的起源和机制至关重要，尤其是在高红移时。我们提供了1.5 GHz非常长的基线阵列（VLBA）图像，从$ z = 5.9 $的无线电连续性发射（RIQ）J2242+0334 j2242+0334。以前在1.5 GHz和3 GHz上都以Karl G. Jansky非常大的阵列（VLA）作为点源检测到了该对象。但是，在VLBA图像中没有明确的检测，即10.7 milliarcsecond（MAS）$ \ times $ \ times $ 4.5 MAS（61.7 PC $ \ times $ 26.0 PC）和26 Mas $ \ tims $ \ tims $ \ times $ \ times $ \ times $ \ times $ 21 MAS（150 PC $ \ times $ \ times $ 121 $ 121 PC）。这表明，与$3σ$检测极限相比，从整个分辨率图像中的40.5 $μ\ rm jy \ rm jy \ rm jy \ rm jy \ rm jy \ rm jy \ rm jy \ rm \ rm thecection限制的MAS尺度上的无线电发射是分散的。 RIQ J2242+0334中的无线电发射可能是风的（即扩散），而不是以准确的喷气机的形式。这与以前对最发光的类星体（$ z \ sim 6 $ 6）的无线电检测不同，该检测通常由紧凑的高亮度温度无线电源主导。同时，与低红移处的RIQ相比，J2242+0334的情况表明并非所有RIQ都均为射线射线广播。这种光学微弱的RIQ提供了一个重要且独特的例子，可以在最早的宇宙时代研究不太强大的活性银河核中的无线电活动。
High-resolution imaging is crucial for exploring the origin and mechanism of radio emission in quasars, especially at high redshifts. We present 1.5 GHz Very Long Baseline Array (VLBA) images of the radio continuum emission from the radio-intermediate quasar (RIQ) J2242+0334 at $z = 5.9$. This object was previously detected at both 1.5 GHz and 3 GHz with the Karl G. Jansky Very Large Array (VLA) as a point source. However, there is no clear detection in the VLBA images at both the full resolution of 10.7 milliarcsecond (mas) $\times$ 4.5 mas (61.7 pc $\times$ 26.0 pc) and a tapered resolution of 26 mas $\times$ 21 mas (150 pc $\times$ 121 pc). This suggests that the radio emission from the quasar is diffuse on mas scales with surface brightness fainter than the $3σ$ detection limit of 40.5 $μ\rm Jy \ beam^{-1}$ in the full resolution image. The radio emission in the RIQ J2242+0334 is likely to be wind-like (i.e., diffuse) rather than in the form of collimated jets. This is different from the previous radio detections of the most luminous quasars at $z \sim$6 which are usually dominated by compact, high brightness temperature radio sources. Meanwhile, compared with RIQs at low redshifts, the case of J2242+0334 suggests that not all RIQs are beamed radio-quiet quasars. This optically faint RIQ provides an important and unique example to investigate the radio activity in the less powerful active galactic nuclei at the earliest cosmic epoch.
