Earth through the looking glass: how frequently are we detected by other civilizations through photometric microlensing?
Earth through the looking glass: how frequently are we detected by other civilizations through photometric microlensing?
复制标题
透过镜子看地球：我们被其他文明通过光度微透镜探测到的频率有多高？
DOI：
10.1093/mnras/stac1855
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发表时间：
2022
影响因子：
4.8
通讯作者：
Suphapolthaworn S
中科院分区：
文献类型：
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作者：
Suphapolthaworn S
微透镜被证明是探测银河系中最常见恒星周围的遥远、低质量行星的最佳技术之一。原则上，地球的微透镜信号可以为其他科技文明提供跨越银河系找到地球的机会。我们考虑地球的光度微透镜信号到其他潜在的技术文明，并将我们银河系中地球光度微透镜信号最容易被观测到的区域称为“地球微透镜区”（EMZ）。EMZ可以被认为是地球过境区（ETZ）的微透镜模拟，从那里观察者看到地球过境太阳。就像ETZ一样，EMZ可以代表一个博弈论的谢林点，用于目标搜寻地外智慧生物（SETI）。为了计算EMZ，我们使用星等g < 20的gaiadr2星表生成地球微透镜概率图和其他观测者的探测率图。虽然我们的太阳系是一个多行星系统，但我们表明，地球的光度微透镜特征几乎总是很好地近似于二元透镜假设。然后，我们用与我们自己的技术相当的技术向观察者展示，地球实际上是隐藏得很好的。具体来说，即使观测者位于g < 20的每颗gaiadr2恒星周围，我们预计来自地球的光度微透镜特征平均每年只能被任何一个观测到10次。此外，emz与银河系中心附近的ETZ重叠，这可能是未来SETI搜索的主要区域。
Microlensing is proving to be one of the best techniques to detect distant, low-mass planets around the most common stars in the Galaxy. In principle, Earth’s microlensing signal could offer the chance for other technological civilizations to find the Earth across Galactic distances. We consider the photometric microlensing signal of Earth to other potential technological civilizations and dub the regions of our Galaxy from which Earth’s photometric microlensing signal is most readily observable as the ‘Earth microlensing zone’ (EMZ). The EMZ can be thought of as the microlensing analogue of the Earth Transit Zone (ETZ) from where observers see Earth transit the Sun. Just as for the ETZ, the EMZ could represent a game-theoretic Schelling point for targeted searches for extra-terrestrial intelligence (SETI). To compute the EMZ, we use theGaiaDR2 catalogue with magnitudeG< 20 to generate Earth microlensing probability and detection rate maps to other observers. While our Solar system is a multiplanet system, we show that Earth’s photometric microlensing signature is almost always well approximated by a binary lens assumption. We then show that the Earth is in fact well hidden to observers with technology comparable to our own. Specifically, even if observers are located around everyGaiaDR2 star withG< 20, we expect photometric microlensing signatures from the Earth to be observable on average only tens per year by any of them. In addition, the EMZs overlap with the ETZ near the Galactic Centres which could be the main areas for future SETI searches.