KMT-2021-BLG-1077L: The fifth confirmed multiplanetary system detected by microlensing
Creators: name: Han, Cheongho
name: Gould, Andrew
name: Bond, Ian A.
name: Jung, Youn Kil
name: Albrow, Michael D.
name: Chung, Sun-Ju
name: Hwang, Kyu-Ha
name: Ryu, Yoon-Hyun
name: Shin, In-Gu
name: Shvartzvald, Yossi
name: Yee, Jennifer C.
name: Zang, Weicheng
name: Cha, Sang-Mok
name: Kim, Dong-Jin
name: Kim, Seung-Lee
name: Lee, Chung-Uk
name: Lee, Dong-Joo
name: Lee, Yongseok
name: Park, Byeong-Gon
name: Pogge, Richard W.
name: Kim, Doeon
name: Abe, Fumio
name: Barry, Richard K.
name: Bennett, David P.
name: Bhattacharya, Aparna
name: Fujii, Hirosane
name: Fukui, Akihiko
name: Hirao, Yuki
name: Itow, Yoshitaka
name: Kirikawa, Rintaro
name: Koshimoto, Naoki
name: Kondo, Iona
name: Matsubara, Yutaka
name: Matsumoto, Sho
name: Miyazaki, Shota
name: Muraki, Yasushi
name: Olmschenk, Greg
name: Okamura, Arisa
name: Ranc, Clément
name: Rattenbury, Nicholas J.
name: Satoh, Yuki
name: Silva, Stela Ishitani
name: Sumi, Takahiro
name: Suzuki, Daisuke
name: Toda, Taiga
name: Tristram, Paul J.
name: Vandorou, Aikaterini
name: Yama, Hibiki
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: The high-magnification microlensing event KMT-2021-BLG-1077 exhibits a subtle and complex anomaly pattern in the region around the peak. We analyze the lensing light curve of the event with the aim of revealing the nature of the anomaly. We test various models in combination with several interpretations. We find that the anomaly cannot be explained by the usual three-body (2L1S and 1L2S) models. The 2L2S model improves the fit compared to the three-body models, but it still leaves noticeable residuals. On the other hand, the 3L1S interpretation yields a model explaining all the major anomalous features in the lensing light curve. According to the 3L1S interpretation, the estimated mass ratios of the lens companions to the primary are $\sim 1.56 \times 10^{-3}$ and $\sim 1.75 \times 10^{-3}$, which correspond to $\sim 1.6$ and $\sim 1.8$ times the Jupiter/Sun mass ratio, respectively, and therefore the lens is a multiplanetary system containing two giant planets. With the constraints of the event time-scale and angular Einstein radius, it is found that the host of the lens system is a low-mass star of mid-to-late M spectral type with a mass of $M_{\rm h} = 0.14^{+0.19}_{-0.07}~M_\odot$, and it hosts two gas giant planets with masses of $M_{\rm p_1}=0.22^{+0.31}_{-0.12}~M_{\rm J}$ and $M_{\rm p_2}=0.25^{+0.35}_{-0.13}~M_{\rm J}$. The planets lie beyond the snow line of the host with projected separations of $a_{\perp, {\rm p}_1}=1.26^{+1.41}_{-1.08}~{\rm AU}$ and $a_{\perp, {\rm p}_2}=0.93^{+1.05}_{-0.80}~{\rm AU}$. The planetary system resides in the Galactic bulge at a distance of $D_{\rm L}=8.24^{+1.02}_{-1.16}~{\rm kpc}$. The lens of the event is the fifth confirmed multiplanetary system detected by microlensing following OGLE-2006-BLG-109L, OGLE-2012-BLG-0026L, OGLE-2018-BLG-1011L, and OGLE-2019-BLG-0468L.
description: 9 pages, 8 figures