通过超稀疏星系进行星系外微透镜效应
Extragalactic microlensing through Ultra Diffuse Galaxies
AI总结：
本文探讨了通过本地超稀疏星系（UDGs）观测中等红移星系的微透镜效应，发现UDGs可能作为微透镜事件的探测目标，但预计事件率较低，需进一步观测。
摘要：
恒星微透镜效应是一种强有力的工具，用于约束致密暗物质模型、揭示双星和系外行星在caustic交叉事件期间。在宇宙学距离上，詹姆斯·韦伯空间望远镜（JWST）常规检测到在巨大透镜簇后方被放大星系中的微透镜巨星级恒星。本文首次探索了通过本地超稀疏星系（UDGs）观测中等红移星系的微透镜效应。使用UDG NGC1052-DF2作为案例研究，我们发现通过UDGs检测微透镜事件是可能的。然而，对于典型的JWST约29 mag访问，其五个背景星系的总微透镜事件率预计为约5.6×10⁻² yr⁻¹，而Vera Rubin Legacy Survey of Space and Time（LSST）的检测率预计为约2×10⁻⁸ yr⁻¹，因此NGC1052-DF2可能不是首选目标，鉴于其缺乏低红移背景星系。Euclid适合识别通过本地星系观测的低红移恒星形成星系样本，以进行更深入的随访观测。我们的零阶计算估计，在LSST监控下，整个天空每年预计有O(1-10)个事件。最后，我们推测UDG微透镜效应将允许对低质量范围的初始质量函数（IMF）和恒星多重性进行独立估计，这对UDG星系有重要价值，包括在某些情况下恒星质量可能主导暗物质的案例，如NGC1052-DF2。
英文摘要：
Stellar microlensing is a powerful method to constrain compact dark matter models, uncover binary stars, and exoplanets during caustic crossing events. At cosmological distances, {\it James-Webb Space Telescope} ({\it JWST}) is routinely detecting microlensed giant stars in highly magnified galaxies behind massive lensing clusters. Here, we explore for the first time microlensing in modest redshift galaxies commonly seen through local Ultra Diffuse Galaxies (UDGs). Using the UDG NGC1052-DF2 as a proof-of-concept, we find that detecting microlensing events through UDGs is possible. Euclid is ideal for identifying samples of low-redshift star-forming galaxies seen through local galaxies for deeper cadenced follow-up, where our zeroth-order calculation estimates that $\mathcal{O}(1-10)$ events per year are expected over the whole sky under the monitoring of LSST, assuming all UDGs share similar distance and stellar content as NGC1052-DF2. Such measurements can help settle the DM issue for UDG galaxies by providing a stellar mass estimate weighted more by the low end of the stellar initial mass function (IMF) than standard stellar synthesis estimates. Note, lower efficiency is estimated for {\it JWST} of $\sim 5.6\times10^{-2}\,\textrm{yr}^{-1}$ over its five background galaxies is expected for typical {\it JWST}$\sim29$\,mag visits, and a low Vera Rubin Legacy Survey of Space and Time (LSST) detection rate of$\sim 0.03\,\textrm{yr}^{-1}$ such that NGC1052-DF2 might not be a prime target given its lack of low-redshift background galaxies.
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