KMT-2022-BLG-0440Lb: A new q < 10−4 microlensing planet with the central-resonant caustic degeneracy broken

Authors

Jiyuan Zhang, Tsinghua University
Weicheng Zang, Tsinghua University
Youn Kil Jung, Korea Astronomy and Space Science Institute
Hongjing Yang, Tsinghua University
Andrew Gould, Max Planck Institute for Astronomy
Takahiro Sumi, The University of Osaka
Shude Mao, Tsinghua University
Subo Dong, Peking University
Michael D. Albrow, University of Canterbury
Sun Ju Chung, Korea Astronomy and Space Science Institute
Cheongho Han, Chungbuk National University
Kyu Ha Hwang, Korea Astronomy and Space Science Institute
Yoon Hyun Ryu, Korea Astronomy and Space Science Institute
In Gu Shin, Harvard-Smithsonian Center for Astrophysics
Yossi Shvartzvald, Weizmann Institute of Science Israel
Jennifer C. Yee, Harvard-Smithsonian Center for Astrophysics
Sang Mok Cha, Korea Astronomy and Space Science Institute
Dong Jin Kim, Korea Astronomy and Space Science Institute
Hyoun Woo Kim, Korea Astronomy and Space Science Institute
Seung Lee Kim, Korea Astronomy and Space Science Institute
Chung Uk Lee, Korea Astronomy and Space Science Institute
Dong Joo Lee, Korea Astronomy and Space Science Institute
Yongseok Lee, Korea Astronomy and Space Science Institute
Byeong Gon Park, Korea Astronomy and Space Science Institute
Richard W. Pogge, The Ohio State University
Qiyue Qian, Tsinghua University
Zhuokai Liu, Peking University
Dan Maoz, Tel Aviv University
Matthew T. Penny, Louisiana State University
Wei Zhu, Tsinghua University
Fumio Abe, Nagoya University
Richard Barry, NASA Goddard Space Flight Center
David P. Bennett, NASA Goddard Space Flight Center

Document Type

Article

Publication Date

7-1-2023

Abstract

We present the observations and analysis of a high-magnification microlensing planetary event, KMT-2022-BLG-0440, for which the weak and short-lived planetary signal was covered by both the KMTNet survey and follow-up observations. The binary-lens models with a central caustic provide the best fits, with a planet/host mass ratio, q = 0.75-1.00 × 10⁻⁴ at 1σ. The binary-lens models with a resonant caustic and a brown-dwarf mass ratio are both excluded by Δχ² > 70. The binary-source model can fit the anomaly well but is rejected by the 'colour argument' on the second source. From Bayesian analyses, it is estimated that the host star is likely a K or M dwarf located in the Galactic disc, the planet probably has a Neptune-mass, and the projected planet-host separation is 1.9^+0.6−0.7 or 4.6^+1.4−1.7 au, subject to the close/wide degeneracy. This is the third q < 10⁻⁴ planet from a high-magnification planetary signal (A ≳ 65). Together with another such planet, KMT-2021-BLG-0171Lb, the ongoing follow-up program for the KMTNet high-magnification events has demonstrated its ability to detect high-magnification planetary signals for q < 10⁻⁴ planets, which are challenging for the current microlensing surveys.

Publication Source (Journal or Book title)

Monthly Notices of the Royal Astronomical Society

First Page

6055

Last Page

6069

Recommended Citation

Zhang, J., Zang, W., Jung, Y., Yang, H., Gould, A., Sumi, T., Mao, S., Dong, S., Albrow, M., Chung, S., Han, C., Hwang, K., Ryu, Y., Shin, I., Shvartzvald, Y., Yee, J., Cha, S., Kim, D., Kim, H., Kim, S., Lee, C., Lee, D., Lee, Y., Park, B., Pogge, R., Qian, Q., Liu, Z., Maoz, D., Penny, M., Zhu, W., Abe, F., Barry, R., & Bennett, D. (2023). KMT-2022-BLG-0440Lb: A new q < 10−4 microlensing planet with the central-resonant caustic degeneracy broken. Monthly Notices of the Royal Astronomical Society, 522 (4), 6055-6069. https://doi.org/10.1093/mnras/stad1398