[论文解读] Gaia Data Release 3 Properties and validation of the radial velocities

D. Katz, P. Sartoretti+48 more|arXiv (Cornell University)|Jun 13, 2022

Stellar, planetary, and galactic studies参考文献 1被引用 108

一句话总结

这篇论文描述 Gaia DR3 径向速度，包括新管线升级、处理选择、校准改进，以及结果的速度性能与对外部调查的验证。

ABSTRACT

Gaia Data Release 3 (Gaia DR3) contains the second release of the combined radial velocities. It is based on the spectra collected during the first 34 months of the nominal mission. The longer time baseline and the improvements of the pipeline made it possible to push the processing limit, from Grvs = 12 in Gaia DR2, to Grvs = 14 mag. In this article, we describe the new functionalities implemented for Gaia DR3, the quality filters applied during processing and post-processing and the properties and performance of the published velocities. For Gaia DR3, several functionalities were upgraded or added. (Abridged) Gaia DR3 contains the combined radial velocities of 33 812 183 stars. With respect to Gaia DR2, the interval of temperature has been expanded from Teff \in [3600, 6750] K to Teff \in [3100, 14500] K for the bright stars ( Grvs \leq 12 mag) and [3100, 6750] K for the fainter stars. The radial velocities sample a significant part of the Milky Way: they reach a few kilo-parsecs beyond the Galactic centre in the disc and up to about 10-15 kpc vertically into the inner halo. The median formal precision of the velocities is of 1.3 km/s at Grvs = 12 and 6.4 km/s at Grvs = 14 mag. The velocity zero point exhibits a small systematic trend with magnitude starting around Grvs = 11 mag and reaching about 400 m/s at Grvs = 14 mag. A correction formula is provided, which can be applied to the published data. The Gaia DR3 velocity scale is in satisfactory agreement with APOGEE, GALAH, GES and RAVE, with systematic differences that mostly do not exceed a few hundreds m/s. The properties of the radial velocities are also illustrated with specific objects: open clusters, globular clusters as well as the Large Magellanic Cloud (LMC). For example, the precision of the data allows to map the line-of-sight rotational velocities of the globular cluster 47 Tuc and of the LMC.

研究动机与目标

• 描述 Gaia DR3 光谱管线在径向速度方面的增强。
• 详细说明 Gaia DR3 处理中应用的质量过滤器与验证程序。
• 表征已发表径向速度的准确性、精度与零点行为。
• 提供开星团、球状星团与 LMC 的径向速度性能示例。
• 提供关于应用零点校正与解释 DR3 速度的指导。

提出的方法

• 升级并描述 DR3 光谱管线包括 SourceInit、EpochInit 与四个科学工作流。
• 实现背景（散光）时序标定和改进的 G_RVS 等级校准。
• 引入重叠光谱的去混合以在截断窗口中恢复多源。
• 公布两种径向速度推导方法：对明星（GRVS≤12）使用历元中位数速度，对较暗星（GRVS 12–14）使用互相关平均值。
• 通过 reDetermineApHotStars 的重新确定与在 gaia_source 中存储模板参数来改进热星的模板选择。

实验结果

研究问题

• RQ1 在 GRVS 范围 12–14 等级的 Gaia DR3 径向速度的质量与可靠性如何？
• RQ2 DR3 径向速度与外部调查（APOGEE、GALAH、GES、RAVE）在系统误差与零点方面有何比较？
• RQ3 仪器标定（散光、跨扫描的 LSF、光谱重叠）如何影响速度的准确性与精度？
• RQ4 DR3 径向速度样本的规模及其天空/恒星群体覆盖范围是多少？
• RQ5 去混合光谱与模板匹配方法对热星与暗星的已发表径向速度有何影响？

主要发现

• Gaia DR3 发布了 33,812,183 个组合径向速度。
• 中位形式精度在 GRVS=12 时为 1.3 km/s，在 GRVS=14 时为 6.4 km/s。
• 径向速度零点显示出一个随幅度依赖的趋势，起始于 GRVS≈11，达到 GRVS=14 时约 400 m/s。
• DR3 速度与 APOGEE、GALAH、GES、RAVE 较为一致，系统误差通常为几百 m/s 或更少。
• 背景校准改进和去混合增加了贡献到径向速度的光谱数量。
• 开/球状星团与 LMC 被用来说明速度性能，包括对 47 Tuc 与 LMC 的视线旋转映射。