通过多波段透镜测光实现微引力透镜透镜体的金属丰度测量
Enabling Metallicity Measurements of M-dwarf Microlensing Lenses out to the Galactic Bulge
- Tsinghua University（清华大学）
- Westlake University（西湖大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
该研究提出测光-微引力透镜金属丰度方法，结合多波段测光与角爱因斯坦半径，可测量银核区M型矮星透镜的金属丰度，计划通过Roman望远镜观测实现约150个行星系统的金属丰度测量，以研究冷巨行星的发生率-金属丰度关系。
AI中文摘要：
我们提出了测光-微引力透镜金属丰度方法，该方法结合M型矮星透镜的多波段测光与角爱因斯坦半径，可实现银核区M型矮星透镜体的金属丰度测量。M型矮星的冷大气包含丰富分子，其宽吸收带使得它们在光学-近红外色-绝对星等图中的位置对金属丰度敏感。角爱因斯坦半径提供了推导透镜绝对星等所需的质量-距离约束，而M型矮星本征轨迹与红化向量在色-色空间中不平行，可从透镜的多波段测光同时推导出其消光和本征颜色，从而恢复透镜在金属丰度敏感的色-绝对星等图中的本征位置。该方法需要覆盖R、Z、K波段的三波段透镜测光，结合Roman望远镜的高分辨率F062、F087和F213成像，特别适合Roman望远镜开展相关研究。根据Roman望远镜计划的银核时域巡天（GBTDS）观测，加上Roman望远镜发射约十年后每个天区额外约8小时的F062成像（总计约40小时），基于GBTDS的产量预测，可对约150个行星系统测量其宿主金属丰度，模拟恢复分析显示典型1σ精度约为0.25 dex。将该方法均匀应用于GBTDS中已探测到行星和未探测到行星的微引力透镜事件，将首次测量雪线以外冷巨行星的发生率-金属丰度关系，约束其形成的低金属丰度截止值，并将发生率-金属丰度研究扩展到银河系内部。
英文摘要：
We demonstrate that metallicity becomes identifiable for M-dwarf microlensing lenses out to bulge distances when multi-band lens photometry is combined with the angular Einstein radius, thereby defining the photometric--microlensing metallicity method. The cool atmospheres of M dwarfs contain abundant molecules, whose broad absorption bands make their positions in an optical--NIR color--absolute magnitude diagram sensitive to metallicity. The angular Einstein radius provides the mass--distance constraint needed to infer the lens absolute magnitude, while the intrinsic M-dwarf locus and reddening vector are non-parallel in color--color space, allowing the lens extinction and intrinsic color to be inferred simultaneously from its multi-band photometry, thereby recovering the lens intrinsic position in the metallicity-sensitive color--absolute magnitude diagram. The method requires three-band lens photometry spanning roughly the R, Z, and K bands, making it particularly well suited to Roman through its high-resolution F062, F087, and F213 imaging. With the planned Roman Galactic Bulge Time-Domain Survey (GBTDS) observations plus an additional $\sim$8 hr of F062 imaging per field ($\sim$40 hr in total) roughly a decade after Roman launch, host metallicities could be measured for $\sim$150 planetary systems under the GBTDS yield forecast, with a typical $1σ$ precision of $\sim$0.25 dex from our mock-recovery analysis. Applied homogeneously to GBTDS microlensing events with and without detected planets, the method would enable the first measurement of the occurrence--metallicity relation for cold low-mass planets beyond the snow line, constrain the low-metallicity cutoff for their formation, and extend occurrence--metallicity studies into the inner Galaxy.
