arXiv 1909.020102019-09astro-ph.GA

来自Gaia和unWISE数据的活动星系核星表

Catalogues of Active Galactic Nuclei From Gaia and unWISE Data

Yiping Shu, Sergey E. Koposov, N. Wyn Evans, Vasily Belokurov, Richard G. McMahon, Matthew W. Auger, Cameron A. Lemon

备注：: 18 pages+appendices, 11 figures, 2 tables, published by the MNRAS. The previous link to the catalogue is no longer valid. The C75 catalogue can be downloaded from this new link: at https://zenodo.org/record/6837642#.YtEgjy8RrzI
DOI：: 10.1093/mnras/stz2487

摘要：

本文介绍了两个活动星系核（AGN）候选星表，它们是从\emph{Gaia}任务的Data Release 2（DR 2）和\emph{Wide-field Infrared Survey Explorer}（\emph{WISE}）的unWISE星表中选出的。我们训练一个随机森林分类器来预测\emph{Gaia} -unWISE联合样本中每个源是活动星系核的概率，$P_{\rm RF}$，基于\emph{Gaia}天体测量和光度测量以及unWISE光度测量。这两个目录，我们指定为C75和R85，通过应用不同的$P_{\rm RF}$阈值切割来构建，以分别实现75%的总体完整性（在\emph{Gaia} $G\leq20$ mag下$\approx$ 90%）和85%的可靠性。C75（R85）星表在36，000度$^2$有效天区包含2，734，464（2，182，193）个活动星系核候选者，其中$\approx$ 91（0.52）万是新发现的。利用\emph{Gaia}和\emph{WISE}的星等和颜色，通过随机森林回归，得到了候选活动星系核的光度红移。总的测光红移精度估计为0.11。交叉匹配的活动星系核候选者与已知的明亮的星系团的样本，我们确定了一个高概率的强透镜活动星系核候选者系统，SDSS\，J1326 $+$ 4806，与一个大的图像分离的21 \farcs 06。在我们的星表中的所有候选活动星系核在任务结束时都将具有来自\emph{Gaia}的$\sim$ 5年长的光变曲线，因此将是活动星系核变率研究的重要资源。我们的AGN目录也将有助于AGN目标的选择，为未来的光谱调查，特别是在南半球。C75目录可在https://zenodo.org/record/6837642#.YtEgjy8RrzI下载。

英文摘要：

We present two catalogues of active galactic nucleus (AGN) candidates selected from the latest data of two all-sky surveys -- Data Release 2 (DR2) of the \emph{Gaia} mission and the unWISE catalogue of the \emph{Wide-field Infrared Survey Explorer} (\emph{WISE}). We train a random forest classifier to predict the probability of each source in the \emph{Gaia}-unWISE joint sample being an AGN, $P_{\rm RF}$, based on \emph{Gaia} astrometric and photometric measurements and unWISE photometry. The two catalogues, which we designate C75 and R85, are constructed by applying different $P_{\rm RF}$ threshold cuts to achieve an overall completeness of 75\% ($\approx$90\% at \emph{Gaia} $G\leq20$ mag) and reliability of 85\% respectively. The C75 (R85) catalogue contains 2,734,464 (2,182,193) AGN candidates across the effective 36,000 deg$^2$ sky, of which $\approx$0.91 (0.52) million are new discoveries. Photometric redshifts of the AGN candidates are derived by a random forest regressor using \emph{Gaia} and \emph{WISE} magnitudes and colours. The estimated overall photometric redshift accuracy is 0.11. Cross-matching the AGN candidates with a sample of known bright cluster galaxies, we identify a high-probability strongly-lensed AGN candidate system, SDSS\,J1326$+$4806, with a large image separation of 21\farcs06. All the AGN candidates in our catalogues will have $\sim$5-year long light curves from \emph{Gaia} by the end of the mission, and thus will be a great resource for AGN variability studies. Our AGN catalogues will also be helpful in AGN target selections for future spectroscopic surveys, especially ones in the southern hemisphere. The C75 catalogue can be downloaded at https://zenodo.org/record/6837642#.YtEgjy8RrzI.

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