论文标题
候选紧凑型对称对象的可变性和parsec尺度的无线电结构
Variability and parsec-scale radio structure of candidate compact symmetric objects
论文作者
论文摘要
我们报告了多上述非常大的阵列（VLA）和PC尺度非常长的基线阵列（VLBA）观察到候选紧凑型对称对象（CSO），来自高频峰值机的微弱样本。新的VLBA观测值可以在约42％的观察到来源中解析无线电结构，显示可能是迷你叶子或核心射流结构的双分量。 VLA监控的几乎所有来源都显示了十年的时间尺度上的一些可变性，只有1个来源没有显示出任何显着变化。在17个来源中，磁通量密度随着在Blazars的预期而随机变化，并且在4个来源中，在最后一个观察时期的频谱变得平坦，证实了在GHz制度中选择的样品受到光束物体的高度污染。在16个对象中，PC尺度和可变性属性与绝热膨胀中的年轻无线电源一致，并且光谱的光学薄弱部分的通量密度稳定下降，并且光学厚度部分的通量密度增加。对于这些来源，我们估计几十到几百年的动态年龄。相应的膨胀速度通常在0.1C和0.7C之间，类似于具有不同方法的CSO中的值。我们在某些CSO候选人中观察到的快速演变表明，并非所有对象都会成为古典的Fanaroff-Riley无线电来源。
We report results on multi-epoch Very Large Array (VLA) and pc-scale Very Long Baseline Array (VLBA) observations of candidate compact symmetric objects (CSOs) from the faint sample of high frequency peakers. New VLBA observations could resolve the radio structure in about 42 per cent of the observed sources, showing double components that may be either mini-lobes or core-jet structures. Almost all the sources monitored by the VLA show some variability on time scale of a decade, and only 1 source does not show any significant variation. In 17 sources the flux density changes randomly as it is expected in blazars, and in 4 sources the spectrum becomes flat in the last observing epoch, confirming that samples selected in the GHz regime are highly contaminated by beamed objects. In 16 objects, the pc-scale and variability properties are consistent with a young radio source in adiabatic expansion, with a steady decrease of the flux density in the optically-thin part of the spectrum, and a flux density increase in the optically-thick part. For these sources we estimate dynamical ages between a few tens to a few hundreds years. The corresponding expansion velocity is generally between 0.1c and 0.7c, similar to values found in CSOs with different approaches. The fast evolution that we observe in some CSO candidates suggests that not all the objects would become classical Fanaroff-Riley radio sources.
