论文标题
一种检查无线电AGN的高还原标识的方法
A method for checking high-redshift identification of radio AGNs
论文作者
论文摘要
在大规模的光谱调查中，由于其发射线的弱点和所使用的不同自动识别算法，发现许多物体具有多个红移测量。这些包括一些可疑的高红移（z> = 5）主动银河核（AGNS）。在这里，我们提出了一种检查此类来源的高红移识别的方法，前提是它们是无线电大风并且具有很长的基线干涉法（VLBI）成像的观测值，对其Milli-Arcsec（MAS）刻度射流结构可在多个时期提供。该方法基于喷射成分适当运动的确定，以及喷气物理学（观察到的批量洛伦兹因子的最大值）和宇宙学（早期宇宙中观察到现象的时间扩张）的结合限制了明显适当运动的可能值。例如，我们介绍了用两种不同的红移报告的Quasar J2346+0705的情况，$ z_ {1} = 5.063 $和$ z_ {2} = 0.171 $，在文献中。我们通过利用从2014年到2018年获取的VLBI数据来测量其无线电飞机中三个组件的明显正确动作（$μ$）。我们获得了$μ__{J1} = 0.334 \ pm 0.099 $ 0.099 $ MAS yr $ yr $ yr $^{ - 1}} $μ_{J3} = 0.060 \ pm 0.005 $ mas yr $^{ - 1} $。最大适当的运动将转换为$β_ {\ rm app} = 41.2 \ pm12.2 \，c $的明显横向速度。如果源位于Redshift 5.063。该值超过了迄今已知的Blazar喷射速度。该论点和其他参数表明J2346+0705由低红色的银河系托管。我们的方法可能适用于缺乏明确的光谱红移测定或仅具有光度红移估计值的其他高红移AGN候选者，但显示出突出的无线电飞机，允许对快速喷射适当运动的VLBI测量。
In large-scale optical spectroscopic surveys, there are many objects found to have multiple redshift measurements due to the weakness of their emission lines and the different automatic identification algorithms used. These include some suspicious high-redshift (z >= 5) active galactic nuclei (AGNs). Here we present a method for inspecting the high-redshift identification of such sources provided that they are radio-loud and have very long baseline interferometry (VLBI) imaging observations of their milli-arcsec (mas) scale jet structure available at multiple epochs. The method is based on the determination of jet component proper motions, and the fact that the combination of jet physics (the observed maximal values of the bulk Lorentz factor) and cosmology (the time dilation of observed phenomena in the early Universe) constrain the possible values of apparent proper motions. As an example, we present the case of the quasar J2346+0705 that was reported with two different redshifts, $z_{1} = 5.063$ and $z_{2} = 0.171$, in the literature. We measured the apparent proper motions ($μ$) of three components identified in its radio jet by utilizing VLBI data taken from 2014 to 2018. We obtained $μ_{J1} = 0.334 \pm 0.099$ mas yr$^{-1}$, $μ_{J2} = 0.116 \pm 0.029$ mas yr$^{-1}$, and $μ_{J3} = 0.060 \pm 0.005$ mas yr$^{-1}$. The maximal proper motion is converted to an apparent transverse speed of $β_{\rm app} = 41.2\pm12.2\,c$. if the source is at redshift 5.063. This value exceeds the blazar jet speeds known to date. This and other arguments suggest that J2346+0705 is hosted by a low-redshift galaxy. Our method may be applicable for other high-redshift AGN candidates lacking unambiguous spectroscopic redshift determination or having photometric redshift estimates only, but showing prominent radio jets allowing for VLBI measurements of fast jet proper motions.
