Gaia Data Release 3 External calibration of BP/RP low-resolution spectroscopic data
Gaia Data Release 3 External calibration of BP/RP low-resolution spectroscopic data
复制标题
Gaia Data Release 3 BP/RP 低分辨率光谱数据的外部校准
DOI：
10.1051/0004-6361/202243880
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发表时间：
2023
影响因子：
6.5
通讯作者：
Montegriffo P
中科院分区：
文献类型：
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作者：
Montegriffo P
盖亚银河巡天任务的设计和优化是为了获得银河系中近20亿颗恒星的天体测量、光度测定和光谱学。然而，作为一项全天多历元巡天，盖亚还观测到数百万个G ~ 21等的河外天体。由于盖亚机载选择算法的性质，这些天体大多是点源状天体。利用卫星提供的数据，我们通过监督机器学习方法识别了类星体和星系候选者，并使用低分辨率BP/RP光谱估计了它们的红移。我们进一步从预定义的输入列表中表征类星体和星系的宿主星系的表面亮度分布。本文概述了银河系外天体的处理，描述了Gaia DR3中的数据产品，并分析了它们的特性。两个综合表包含了高完整性但低纯度（50-70%）的主要结果，包括660万个候选类星体和480万个候选星系。我们提供的查询选择了这些包含190万个可能类星体和290万个可能星系的更纯净的子样本（纯度均为95%）。我们还利用4.3万个高概率类星体的高质量BP/RP光谱，在红移范围0.05-4.36之间构建了一个跨越72-1000 nm的复合类星体光谱。
The Gaia Galactic survey mission is designed and optimized to obtain astrometry, photometry, and spectroscopy of nearly two billion stars in our Galaxy. Yet as an all-sky multi-epoch survey, Gaia also observes several million extragalactic objects down to a magnitude of G∼ 21 mag. Due to the nature of the Gaia onboard-selection algorithms, these are mostly point-source-like objects. Using data provided by the satellite, we have identified quasar and galaxy candidates via supervised machine learning methods, and estimate their redshifts using the low resolution BP/RP spectra. We further characterise the surface brightness profiles of host galaxies of quasars and of galaxies from pre-defined input lists. Here we give an overview of the processing of extragalactic objects, describe the data products in Gaia DR3, and analyse their properties. Two integrated tables contain the main results for a high completeness, but low purity (50–70%), set of 6.6 million candidate quasars and 4.8 million candidate galaxies. We provide queries that select purer sub-samples of these containing 1.9 million probable quasars and 2.9 million probable galaxies (both∼ 95% purity). We also use high quality BP/RP spectra of 43 thousand high probability quasars over the redshift range 0.05–4.36 to construct a composite quasar spectrum spanning restframe wavelengths from 72–1000 nm.