Candidate Microlensing Brown Dwarfs in Binary Lens Systems from the 2023–2025 Observing Seasons

Abstract We present detailed light-curve analyses of 10 binary-lens microlensing events observed during the 2023–2025 seasons and selected as candidates for hosting brown dwarf companions. The sample includes OGLE-2023-BLG-0249, KMT-2023-BLG-1246, OGLE-2023-BLG-0079, KMT-2024-BLG-0072, KMT-2024-BLG-0897, KMT-2024-BLG-1876, KMT-2024-BLG-2379, KMT-2025-BLG-0922, KMT-2025-BLG-1056, and KMT-2025-BLG-2427. For each event, we carry out modeling of the light curve, explore relevant degeneracies, and, when finite-source effects are present, determine the angular Einstein radius. For OGLE-2023-BLG-0249, we additionally measure the microlens parallax, which allows a direct determination of the lens masses and distance. For the remaining events, we estimate the physical lens properties via Bayesian analyses incorporating Galactic priors. The resulting posteriors show that the lens companions in all systems have median masses in the brown dwarf regime, and the lenses of two events (KMT-2025-BLG-0922 and KMT-2025-BLG-1056) are consistent with binaries in which both lens components fall within the brown dwarf mass range. Spanning a wide range of projected separations and distances, these detections illustrate the power of high-cadence microlensing surveys to build a census of brown dwarf companions, including faint and distant systems beyond the reach of flux-limited methods.

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Publication Details

Journal
The Astronomical Journal
Published
2026-05-08
DOI
https://doi.org/10.3847/1538-3881/ae5e5d
Primary Topic
Stellar, planetary, and galactic studies
Type
article
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article

Candidate Microlensing Brown Dwarfs in Binary Lens Systems from the 2023–2025 Observing Seasons

S I Silva, Ryunosuke Oishi, J. Paul Tristram, In-Gu Shin et al.
The Astronomical Journal
Stellar, planetary, and galactic studies
article

Candidate Microlensing Brown Dwarfs in Binary Lens Systems from the 2023–2025 Observing Seasons

S I Silva, Ryunosuke Oishi, J. Paul Tristram, In-Gu Shin, S L Kim, Mayu Nishio, M K Szymański, T Sumi, K Ulaczyk, I Soszyński, Asahi Idei, Shuma Makida, Takuto Tamaoki, Yui Okumoto, Seiya Nakayama, Togo Nagano, Radosław Poleski, Michael D. Albrow, A Udalski, Weicheng Zang, Nicholas J. Rattenbury, Dong-Joo Lee, Mariusz Gromadzki, Szymon Kozłowski, Richard W. Pogge, Yongseok Lee, Sean K. Terry, Sang-Mok Cha, Ryo Ogawa, Krzysztof A. Rybicki, (KMTNet Collaboration), Yossi Shvartzvald, Yuki Hirao, (Leading authors), Paweł Pietrukowicz, Yoon-Hyun Ryu, Tutumi Nagai, Yasushi Muraki, Doeon Kim, Shota Miyazaki, Chung-Uk Lee, Kansuke Nunota, Cheongho Han, Przemek Mróz, Jennifer C. Yee, David P. Bennett, Marcin Wrona, Jan Skowron, Mateusz J. Mróz, Kyu-Ha Hwang, Greg Olmschenk, Ryusei Hamada, Fumio Abe, Ian A. Bond, Daisuke Suzuki, Hongjing Yang, Yuki Satoh, Byeong-Gon Park, Dong-Jin Kim, Andrew Gould, Clément Ranc, Youn Kil Jung, Sun-Ju Chung, Aparna Bhattacharya, Patryk Iwanek, (The OGLE Collaboration)
article en

Abstract

Abstract We present detailed light-curve analyses of 10 binary-lens microlensing events observed during the 2023–2025 seasons and selected as candidates for hosting brown dwarf companions. The sample includes OGLE-2023-BLG-0249, KMT-2023-BLG-1246, OGLE-2023-BLG-0079, KMT-2024-BLG-0072, KMT-2024-BLG-0897, KMT-2024-BLG-1876, KMT-2024-BLG-2379, KMT-2025-BLG-0922, KMT-2025-BLG-1056, and KMT-2025-BLG-2427. For each event, we carry out modeling of the light curve, explore relevant degeneracies, and, when finite-source effects are present, determine the angular Einstein radius. For OGLE-2023-BLG-0249, we additionally measure the microlens parallax, which allows a direct determination of the lens masses and distance. For the remaining events, we estimate the physical lens properties via Bayesian analyses incorporating Galactic priors. The resulting posteriors show that the lens companions in all systems have median masses in the brown dwarf regime, and the lenses of two events (KMT-2025-BLG-0922 and KMT-2025-BLG-1056) are consistent with binaries in which both lens components fall within the brown dwarf mass range. Spanning a wide range of projected separations and distances, these detections illustrate the power of high-cadence microlensing surveys to build a census of brown dwarf companions, including faint and distant systems beyond the reach of flux-limited methods.

The Astronomical JournalVol. 171(6)
Centre National de la Recherche Scientifique (FR), Goddard Space Flight Center (US), University of Auckland (NZ), Chungbuk National University (KR), University of Canterbury (NZ), Kanto Gakuin University (JP), Korea Astronomy and Space Science Institute (KR), Japan Aerospace Exploration Agency (JP), Institut d'Astrophysique de Paris (FR), Westlake University (CN), University of Warwick (GB), Sorbonne Université (FR), Center for Astrophysics Harvard & Smithsonian (US), Institute of Space and Astronautical Science (JP), University of Warsaw (PL), Massey University (NZ), The Ohio State University (US), Weizmann Institute of Science (IL), Nagoya University (JP), University of Maryland, College Park (US), The University of Tokyo (JP), Villanova University (US), Korea University of Science and Technology (KR), The University of Osaka (JP)
Openalex Percentile: Top 5%
Stellar, planetary, and galactic studies
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