KMT-2023-BLG-1431Lb: A New q < 10−4 Microlensing Planet from a Subtle Signature

• Published in: Publications of the Astronomical Society of the Pacific 2024-05, Vol.136 (5), p.54402
• Main Authors: Bell, Aislyn, Zhang, Jiyuan, Zang, Weicheng, Jung, Youn Kil, Yee, Jennifer C., Yang, Hongjing, Sumi, Takahiro, Udalski, Andrzej, Albrow, Michael D., Chung, Sun-Ju, Gould, Andrew, Han, Cheongho, Hwang, Kyu-Ha, Ryu, Yoon-Hyun, Shin, In-Gu, Shvartzvald, Yossi, Cha, Sang-Mok, Kim, Dong-Jin, Kim, Seung-Lee, Lee, Chung-Uk, Lee, Dong-Joo, Lee, Yongseok, Park, Byeong-Gon, Pogge, Richard W., Tang, Yunyi, McCormick, Jennie, Dong, Subo, Liu, Zhuokai, de Almeida, Leandro, Mao, Shude, Maoz, Dan, Zhu, Wei, Abe, Fumio, Barry, Richard, Bennett, David P., Bhattacharya, Aparna, Bond, Ian A., Fujii, Hirosane, Fukui, Akihiko, Hamada, Ryusei, Hirao, Yuki, Silva, Stela Ishitani, Itow, Yoshitaka, Kirikawa, Rintaro, Kondo, Iona, Koshimoto, Naoki, Matsubara, Yutaka, Matsumoto, Sho, Miyazaki, Shota, Muraki, Yasushi, Okamura, Arisa, Lmschenk, Greg, Ranc, Clément, Rattenbury, Nicholas J., Satoh, Yuki, Suzuki, Daisuke, Toda, Taiga, Tomoyoshi, Mio, Tristram, Paul J., Vandorou, Aikaterini, Yama, Hibiki, Yamashita, Kansuke, Mróz, Przemek, Skowron, Jan, Poleski, Radoslaw, Szymański, Michał K., Soszyński, Igor, Pietrukowicz, Paweł, Kozłowski, Szymon, Ulaczyk, Krzysztof, Rybicki, Krzysztof A., Iwanek, Patryk, Wrona, Marcin, Gromadzki, Mariusz
• Format: Article
• Language: English
• Subjects: Bayesian analysis; Gravitational microlensing; Gravitational microlensing exoplanet detection; Planets
• ISSN: 0004-6280; 1538-3873
• DOI: 10.1088/1538-3873/ad48b8

The current studies of microlensing planets are limited by small number statistics. Follow-up observations of high-magnification microlensing events can efficiently form a statistical planetary sample. Since 2020, the Korea Microlensing Telescope Network (KMTNet) and the Las Cumbres Observatory (LCO) global network have been conducting a follow-up program for high-magnification KMTNet events. Here, we report the detection and analysis of a microlensing planetary event, KMT-2023-BLG-1431, for which the subtle (0.05 mag) and short-lived (5 hr) planetary signature was characterized by the follow-up from KMTNet and LCO. A binary-lens single-source (2L1S) analysis reveals a planet/host mass ratio of q = (0.72 ± 0.07) × 10 −4 , and the single-lens binary-source (1L2S) model is excluded by Δ χ 2 = 80. A Bayesian analysis using a Galactic model yields estimates of the host star mass of M host = 0.57 − 0.29 + 0.33 M ⊙ , the planetary mass of M planet = 13.5 − 6.8 + 8.1 M ⊕ , and the lens distance of D L = 6.9 − 1.7 + 0.8 kpc. The projected planet-host separation of a ⊥ = 2.3 − 0.5 + 0.5 au or a ⊥ = 3.2 − 0.8 + 0.7 au, subject to the close/wide degeneracy. We also find that without the follow-up data, the survey-only data cannot break the degeneracy of central/resonant caustics and the degeneracy of 2L1S/1L2S models, showing the importance of follow-up observations for current microlensing surveys.