The LOFAR Two-Metre Sky Survey VI. Optical identifications for the second data release
The LOFAR Two-Metre Sky Survey VI. Optical identifications for the second data release
复制标题
LOFAR 两米巡天 VI。
DOI：
10.1051/0004-6361/202347333
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发表时间：
2023
影响因子：
6.5
通讯作者：
Hardcastle M
中科院分区：
文献类型：
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作者：
Hardcastle M
LOFAR 两米巡天 (LoTSS) 的第二次数据覆盖了北部天空的 27%，总面积约为 5700 deg1。 LOFAR 具有荷兰基线（6 角秒）的高角分辨率，使我们能够对大部分检测到的无线电源进行光学识别，而无需进一步的无线电跟踪；然而，由于 LOFAR 图像对扩展结构具有出色的敏感性，因此在 LOFAR 图像中发现了许多扩展无线电源，该过程变得更具挑战性。在本文中，我们基于光学和近红外数据，结合为我们的第一个数据发布开发的似然比交叉匹配方法、我们的公民科学项目射电星系动物园：LOFAR、新的算法光学识别方法以及天文学家的广泛目视检查，提出了基于光学和近红外数据的第二次数据发布中的源关联和源识别。我们还提出了大部分光学识别的光谱或光度红移。该区域共有 4 116 934 个射电源，具有良好的光学数据，其中 85% 具有光学或红外识别，58% 具有良好的红移估计。我们通过将数据集与早期的光学识别无线电勘测进行比较来证明数据集的质量。这是迄今为止最大的光学识别射电目录，并将允许对恒星形成和射电大声的活动星系进行强有力的统计研究。
The second data release of the LOFAR Two-Metre Sky Survey (LoTSS) covers 27% of the northern sky, with a total area of ~5700 deg1. The high angular resolution of LOFAR with Dutch baselines (6 arcsec) allows us to carry out optical identifications of a large fraction of the detected radio sources without further radio followup; however, the process is made more challenging by the many extended radio sources found in LOFAR images as a result of its excellent sensitivity to extended structure. In this paper we present source associations and identifications for sources in the second data release based on optical and near-infrared data, using a combination of a likelihood-ratio cross-match method developed for our first data release, our citizen science project Radio Galaxy Zoo: LOFAR, and new approaches to algorithmic optical identification, together with extensive visual inspection by astronomers. We also present spectroscopic or photometric redshifts for a large fraction of the optical identifications. In total 4 116 934 radio sources lie in the area with good optical data, of which 85% have an optical or infrared identification and 58% have a good redshift estimate. We demonstrate the quality of the dataset by comparing it with earlier optically identified radio surveys. This is by far the largest ever optically identified radio catalogue, and will permit robust statistical studies of star-forming and radio-loud active galaxies.