Two Isolated Microlensing Events Near the Upper Shore of Einstein Desert
Abstract
The Einstein desert is a deficit in the angular Einstein-radius (θE) distribution of isolated objects over the range 9 μas < θE<26 μas. Although this interval contained no events when the desert was first identified, several subsequent detections have fallen within it, raising questions about its detailed structure and requiring a larger detection sample. In this paper, we report the observations and analyses of two microlensing events possibly caused by isolated giant planets or brown dwarfs whose $ θ_{\rm E}$ lie near the upper shore of the desert. MOA-2021-BLG-145 has $ θ_{\rm E} = 23.1\pm2.0 ~{\rm μas}$, placing it just inside the upper boundary, and KMT-2026-BLG-0357 has $ θ_{\rm E} = 36.5\pm 3.7~{\rm μas}$, placing it above the desert. We also compare the $ θ_{\rm E}$ distributions of isolated objects and bound planetary events. The bound population shows no corresponding deficit over the same range, suggesting that the Einstein desert may be associated with the formation or subsequent evolution of the isolated population. Furthermore, some FFPs may lie above the upper shore of the Einstein desert, indicating that a more complete understanding of the FFP population requires direct lens-mass measurements.
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BibTeX
@misc{qian2026isolated,
title = {{Two Isolated Microlensing Events Near the Upper Shore of Einstein Desert}},
author = {Qiyue Qian and Weicheng Zang and Yoon-Hyun Ryu and Takahiro Sumi and Andrzej Udalski and Hongjing Yang and Jiyuan Zhang and Shude Mao and Michael D. Albrow and Sun-Ju Chung and Andrew Gould and Cheongho Han and Kyu-Ha Hwang and Youn Kil Jung and In-Gu Shin and Yossi Shvartzvald and Jennifer C. Yee and Sang-Mok Cha and Dong-Jin Kim and Seung-Lee Kim and Chung-Uk Lee and Dong-Joo Lee and Yongseok Lee and Byeong-Gon Park and Fumio Abe and David P. Bennett and Aparna Bhattacharya and Ian A. Bond and Kotaro Daimon and Chihiro Ueda and Ryusei Hamada and Yuki Hirao and Stela Ishitani Silva and Shuma Makida and Shota Miyazaki and Yasushi Muraki and Seiya Nakayama and Kansuke Nunota and Ryo Ogawa and Ryunosuke Oishi and Hideaki Ose and Greg Olmschenk and Clément Ranc and Nicholas J. Rattenbury and Yuki K. Satoh and Daisuke Suzuki and Takuto Tamaoki and Sean Terry and Paul J. Tristram and Aikaterini Vandorou and Hibiki Yama and Przemek Mróz and Michał K. Szymański and Jan Skowron and Radoslaw Poleski and Igor Soszyński and Paweł Pietrukowicz and Szymon Kozłowski and Krzysztof A. Rybicki and Patryk Iwanek},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.00754},
eprint = {2611.00754},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.00754},
}
RIS
TY - UNPB
TI - Two Isolated Microlensing Events Near the Upper Shore of Einstein Desert
AU - Qiyue Qian
AU - Weicheng Zang
AU - Yoon-Hyun Ryu
AU - Takahiro Sumi
AU - Andrzej Udalski
AU - Hongjing Yang
AU - Jiyuan Zhang
AU - Shude Mao
AU - Michael D. Albrow
AU - Sun-Ju Chung
AU - Andrew Gould
AU - Cheongho Han
AU - Kyu-Ha Hwang
AU - Youn Kil Jung
AU - In-Gu Shin
AU - Yossi Shvartzvald
AU - Jennifer C. Yee
AU - Sang-Mok Cha
AU - Dong-Jin Kim
AU - Seung-Lee Kim
AU - Chung-Uk Lee
AU - Dong-Joo Lee
AU - Yongseok Lee
AU - Byeong-Gon Park
AU - Fumio Abe
AU - David P. Bennett
AU - Aparna Bhattacharya
AU - Ian A. Bond
AU - Kotaro Daimon
AU - Chihiro Ueda
AU - Ryusei Hamada
AU - Yuki Hirao
AU - Stela Ishitani Silva
AU - Shuma Makida
AU - Shota Miyazaki
AU - Yasushi Muraki
AU - Seiya Nakayama
AU - Kansuke Nunota
AU - Ryo Ogawa
AU - Ryunosuke Oishi
AU - Hideaki Ose
AU - Greg Olmschenk
AU - Clément Ranc
AU - Nicholas J. Rattenbury
AU - Yuki K. Satoh
AU - Daisuke Suzuki
AU - Takuto Tamaoki
AU - Sean Terry
AU - Paul J. Tristram
AU - Aikaterini Vandorou
AU - Hibiki Yama
AU - Przemek Mróz
AU - Michał K. Szymański
AU - Jan Skowron
AU - Radoslaw Poleski
AU - Igor Soszyński
AU - Paweł Pietrukowicz
AU - Szymon Kozłowski
AU - Krzysztof A. Rybicki
AU - Patryk Iwanek
PY - 2026
DA - 2026/11/01
PB - arXiv
DO - 10.48550/arxiv.2611.00754
UR - https://arxiv.org/abs/2611.00754
AB - The Einstein desert is a deficit in the angular Einstein-radius (θ_E) distribution of isolated objects over the range 9 μas < θ_E<26 μas. Although this interval contained no events when the desert was first identified, several subsequent detections have fallen within it, raising questions about its detailed structure and requiring a larger detection sample. In this paper, we report the observations and analyses of two microlensing events possibly caused by isolated giant planets or brown dwarfs whose $ θ_{\rm E}$ lie near the upper shore of the desert. MOA-2021-BLG-145 has $ θ_{\rm E} = 23.1\pm2.0 ~{\rm μas}$, placing it just inside the upper boundary, and KMT-2026-BLG-0357 has $ θ_{\rm E} = 36.5\pm 3.7~{\rm μas}$, placing it above the desert. We also compare the $ θ_{\rm E}$ distributions of isolated objects and bound planetary events. The bound population shows no corresponding deficit over the same range, suggesting that the Einstein desert may be associated with the formation or subsequent evolution of the isolated population. Furthermore, some FFPs may lie above the upper shore of the Einstein desert, indicating that a more complete understanding of the FFP population requires direct lens-mass measurements.
ER -