[论文解读] The JWST Galactic Center Survey -- A White Paper

R. Schöedel, Steve Longmore+112 more|arXiv (Cornell University)|Oct 18, 2023

Astronomy and Astrophysical Research被引用 5

一句话总结

本白皮书提出詹姆斯·韦布空间望远镜（JWST）银心 Survey，旨在实现对银河系银心区域数百万颗恒星的亚毫角秒级自行精度，从而实现对恒星族群的运动学研究，直至太阳质量主序星。通过结合JWST/NIRCam与GALACTICNUCLEUS的现有高分辨率天体测量数据，该调查将实现约0.2–0.25 mas/yr的自行精度，彻底革新对银河系中心区域恒星动力学与消光特性的研究。

ABSTRACT

The inner hundred parsecs of the Milky Way hosts the nearest supermassive black hole, largest reservoir of dense gas, greatest stellar density, hundreds of massive main and post main sequence stars, and the highest volume density of supernovae in the Galaxy. As the nearest environment in which it is possible to simultaneously observe many of the extreme processes shaping the Universe, it is one of the most well-studied regions in astrophysics. Due to its proximity, we can study the center of our Galaxy on scales down to a few hundred AU, a hundred times better than in similar Local Group galaxies and thousands of times better than in the nearest active galaxies. The Galactic Center (GC) is therefore of outstanding astrophysical interest. However, in spite of intense observational work over the past decades, there are still fundamental things unknown about the GC. JWST has the unique capability to provide us with the necessary, game-changing data. In this White Paper, we advocate for a JWST NIRCam survey that aims at solving central questions, that we have identified as a community: i) the 3D structure and kinematics of gas and stars; ii) ancient star formation and its relation with the overall history of the Milky Way, as well as recent star formation and its implications for the overall energetics of our galaxy's nucleus; and iii) the (non-)universality of star formation and the stellar initial mass function. We advocate for a large-area, multi-epoch, multi-wavelength NIRCam survey of the inner 100\,pc of the Galaxy in the form of a Treasury GO JWST Large Program that is open to the community. We describe how this survey will derive the physical and kinematic properties of ~10,000,000 stars, how this will solve the key unknowns and provide a valuable resource for the community with long-lasting legacy value.

研究动机与目标

• 利用JWST/NIRCam实现对银河系银心区域恒星的高精度天体测量，直至主序星阶段。
• 通过结合高灵敏度、大视场和改进的天体测量对准，克服以往调查的局限性。
• 为更广泛的天体物理学社区创建一个由社区驱动、开放获取的数据资源。
• 生成高级数据产品，包括校准图像、测光与天体测量星表，以及消光图。
• 利用多历元观测，表征银心区域的红外消光曲线及单颗恒星的消光特性。

提出的方法

• 利用GALACTICNUCLEUS调查（2015/2016年）的现有高精度天体测量数据，作为JWST/NIRCam观测的基准。
• 利用NIRCam的大视场和高灵敏度，实现对H < 18–19 mag恒星的相对天体测量精度小于1 mas。
• 通过结合1 mas的相对天体测量精度、1 mas的对准不确定性，以及五年的观测历元基线，实现自行精度。
• 应用先进的数据还原技术，最大限度减少残余的大气倾斜-平移效应，提升PSF质量。
• 利用超过1,000颗恒星在NIRCam与VLT/HAWK-I数据之间进行交叉校准，降低历元对准误差。
• 开发专门工具用于密集场测光、饱和恒星修复，以及消光曲线表征。

实验结果

研究问题

• RQ1 银河系银心区域的运动学结构在太阳质量主序星尺度下是怎样的？
• RQ2 如何将对暗弱、密集恒星族群的自行精度提升至<0.3 mas/yr？
• RQ3 银河系银心区域的消光详细分布如何？其每颗恒星的消光特性如何变化？
• RQ4 如何最小化多仪器与多历元之间的天体测量对准误差，以实现亚毫角秒级精度？
• RQ5 高精度自行测量对识别共动恒星集团和星团有何影响？

主要发现

• 该调查将实现对亮度H ≤ 18 mag的约80万颗恒星的自行精度约为0.2 mas/yr，对亮度H ≤ 19 mag的约110万颗恒星的自行精度约为0.25 mas/yr。
• 在五年的基线和1 mas的相对天体测量精度下，超过混淆极限（[F210M] ≥ 20–21 mag）的恒星，其自行不确定性将不超过0.35 mas/yr。
• 该调查将使对银河系银心区域的运动学研究可延伸至太阳质量主序星，此前因混淆和灵敏度限制而无法实现。
• JWST/NIRCam与GALACTICNUCLEUS数据的结合，将使约一千万颗恒星的自行测量成为可能。
• 高精度天体测量将使识别共动集团和速度弥散度低至约0.2 mas/yr的恒星族群成为可能。
• 该项目将产出校准图像、天体测量与测光星表，以及详细的消光图，形成持久的社区资源。