论文标题
在Viking调查中的Redshift Z> 6.5类星体的完整搜索
A complete search for redshift z>6.5 quasars in the VIKING survey
论文作者
论文摘要
我们介绍了一个新的，更深入且完整的搜索的结果，以$ 6.5 <z <z <z <9.3 $ quasars超过977deg $^2 $的Vista Kilo-Degegree红外星系（Viking）调查。这利用了一个新的列表驱动数据集，该数据集可在所有频段zyjhks中提供光度法，这是Viking在$ j $中检测到的所有来源。我们使用Mortlock等人的贝叶斯模型比较（BMC）选择方法，仅产生了21个候选人的排名列表。该来源排名第1、2、3和5是该领域的四个已知$ z> 6.5 $ quasars。对其他17名候选人的其他观察，主要是DESI传统调查光度法和ESO FORS2光谱法，确认没有一个是类星体。这是Viking调查中的第一个完整样本，我们提供了计算的选择功能。我们将BMC方法与其他两种选择方法进行了详细比较：颜色剪切和最低$χ^2 $ SED配件。我们发现：i）BMC产生的假阳性比颜色剪裁少八倍，同时达到0.3 mag。更深层次，ii）最低$χ^2 $ sed拟合方法非常有效，但达到0.7 mag。不如BMC方法深，仅选择四个已知类星体之一。我们表明，BMC候选人被拒绝了，因为他们的光度法SED具有很高的$ $^2 $值，其中包括具有非常强大[OIII] $λλ$ 4959,5007在$ y $ band中发射非常强的星系的明亮示例，Matsuoka等人在Fainter Surveys中确定。这是欧几里得搜索中的潜在污染物人群，以前$ z> 7 $ quasars，以前没有考虑到，这需要更好的表征。
We present the results of a new, deeper, and complete search for high-redshift $6.5<z<9.3$ quasars over 977deg$^2$ of the VISTA Kilo-Degree Infrared Galaxy (VIKING) survey. This exploits a new list-driven dataset providing photometry in all bands ZYJHKs, for all sources detected by VIKING in $J$. We use the Bayesian model comparison (BMC) selection method of Mortlock et al., producing a ranked list of just 21 candidates. The sources ranked 1, 2, 3 and 5 are the four known $z>6.5$ quasars in this field. Additional observations of the other 17 candidates, primarily DESI Legacy Survey photometry and ESO FORS2 spectroscopy, confirm that none is a quasar. This is the first complete sample from the VIKING survey, and we provide the computed selection function. We include a detailed comparison of the BMC method against two other selection methods: colour cuts and minimum-$χ^2$ SED fitting. We find that: i) BMC produces eight times fewer false positives than colour cuts, while also reaching 0.3 mag. deeper, ii) the minimum-$χ^2$ SED fitting method is extremely efficient but reaches 0.7 mag. less deep than the BMC method, and selects only one of the four known quasars. We show that BMC candidates, rejected because their photometric SEDs have high $χ^2$ values, include bright examples of galaxies with very strong [OIII]$λλ$4959,5007 emission in the $Y$ band, identified in fainter surveys by Matsuoka et al. This is a potential contaminant population in Euclid searches for faint $z>7$ quasars, not previously accounted for, and that requires better characterisation.
