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arXiv · 2509.18345

A Comprehensive Analysis of Three Microlensing Planet Candidates with the Planet/Binary Degeneracy

Jiyuan Zhang·Weicheng Zang·Yoon-Hyun Ryu·Takahiro Sumi·Andrzej Udalski·Shude Mao·Michael D. Albrow·Sun-Ju Chung·Andrew Gould·Cheongho Han·Kyu-Ha Hwang·Youn Kil Jung·In-Gu Shin·Yossi Shvartzvald·Jennifer C. Yee·Hongjing Yang·Sang-Mok Cha·Dong-Jin Kim·Seung-Lee Kim·Chung-Uk Lee·Dong-Joo Lee·Yongseok Lee·Byeong-Gon Park·Richard W. Pogge·Yunyi Tang·Leandro de Almeida·Dan Maoz·Qiyue Qian·Wei Zhu·Fumio Abe·Ken Bando·David P. Bennett·Aparna Bhattacharya·Ian A. Bond·Akihiko Fukui·Ryusei Hamada·Shunya Hamada·Naoto Hamasaki·Yuki Hirao·Stela Ishitani Silva·Naoki Koshimoto·Yutaka Matsubara·Shota Miyazaki·Yasushi Muraki·Tutumi Nagai·Kansuke Nunota·Greg Olmschenk·Clément Ranc·Nicholas J. Rattenbury·Yuki Satoh·Daisuke Suzuki·Sean K. Terry·Paul J. Tristram·Aikaterini Vandorou·Hibiki Yama·Przemek Mróz·Michał K. Szymański·Jan Skowron·Radoslaw Poleski·Igor Soszyński·Paweł Pietrukowicz·Szymon Kozłowski·Krzysztof A. Rybicki·Patryk Iwanek·Krzysztof Ulaczyk·Marcin Wrona·Mariusz Gromadzki·Mateusz J. Mróz
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Abstract

We present observations and analyses of three high-magnification microlensing events: KMT-2022-BLG-0954, KMT-2024-BLG-0697, and MOA-2024-BLG-018. All three exhibit the "Planet/Binary" degeneracy, with planetary solutions corresponding to mass ratios in the range $-3.7 < \log q < -2.2$, while the binary solutions yield $\log q > -2.0$. For KMT-2022-BLG-0954, we identify a previously unrecognized degeneracy among planetary solutions, involving different mass ratios and normalized source radii. In all three cases, single-lens binary-source models are excluded. Bayesian analyses suggest that the planetary solutions correspond to gas giants orbiting M/K dwarfs beyond the snow line, while KMT-2022-BLG-0954 also admits an alternative interpretation as a super-Earth orbiting a late-type M dwarf. The binary solutions imply a diverse set of systems, including M-dwarf pairs and M-dwarf--brown-dwarf binaries. A review of known events subject to the "Planet/Binary" degeneracy shows that in most cases the degeneracy cannot be resolved through follow-up high-resolution imaging, particularly in the presence of the newly identified degeneracy.

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Jiyuan Zhang, Weicheng Zang, Yoon-Hyun Ryu, Takahiro Sumi, Andrzej Udalski, Shude Mao, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Cheongho Han, Kyu-Ha Hwang, Youn Kil Jung, In-Gu Shin, Yossi Shvartzvald, Jennifer C. Yee, Hongjing Yang, Sang-Mok Cha, Dong-Jin Kim, Seung-Lee Kim, Chung-Uk Lee, Dong-Joo Lee, Yongseok Lee, Byeong-Gon Park, Richard W. Pogge, Yunyi Tang, Leandro de Almeida, Dan Maoz, Qiyue Qian, Wei Zhu, Fumio Abe, Ken Bando, David P. Bennett, Aparna Bhattacharya, Ian A. Bond, Akihiko Fukui, Ryusei Hamada, Shunya Hamada, Naoto Hamasaki, Yuki Hirao, Stela Ishitani Silva, Naoki Koshimoto, Yutaka Matsubara, Shota Miyazaki, Yasushi Muraki, Tutumi Nagai, Kansuke Nunota, Greg Olmschenk, Clément Ranc, Nicholas J. Rattenbury, Yuki Satoh, Daisuke Suzuki, Sean K. Terry, Paul J. Tristram, Aikaterini Vandorou, Hibiki Yama, Przemek Mróz, Michał K. Szymański, Jan Skowron, Radoslaw Poleski, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof A. Rybicki, Patryk Iwanek, Krzysztof Ulaczyk, Marcin Wrona, Mariusz Gromadzki, Mateusz J. Mróz. 2025-09-22. A Comprehensive Analysis of Three Microlensing Planet Candidates with the Planet/Binary Degeneracy. https://arxiv.org/abs/2509.18345

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