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Four Giant Planets from 2024 KMTNet Microlensing Campaign

Cheongho Han, Andrzej Udalski, Ian A. Bond, Chung-Uk Lee, Jiyuan Zhang, Michael D. Albrow, Sun-Ju Chung, Andrew Gould, Youn Kil Jung, Kyu-Ha Hwang, Yoon-Hyun Ryu, Yossi Shvartzvald, In-Gu Shin, Jennifer C. Yee, Weicheng Zang, Hongjing Yang, Doeon Kim, Dong-Jin Kim, Byeong-Gon Park, Przemek Mróz, Michał K. Szymański, Jan Skowron, Radosław Poleski, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof A. Rybicki, Patryk Iwanek, Krzysztof Ulaczyk, Marcin Wrona, Mariusz Gromadzki, Mateusz J. Mróz, Fumio Abe, David P. Bennett, Aparna Bhattacharya, Ryusei Hamada, Stela Ishitani Silva, Yuki Hirao, Asahi Idei, Shota Miyazaki, Yasushi Muraki, Tutumi Nagai, Kansuke Nunota, Greg Olmschenk, Clément Ranc, Nicholas J. Rattenbury, Yuki Satoh, Takahiro Sumi, Daisuke Suzuki, Takuto Tamaoki, Sean K. Terry, Paul J. Tristram, Aikaterini Vandorou, Hibiki Yama, Yuchen Tang, Yunyi Tang, Shude Mao, Dan Maoz, Wei Zhu

TL;DR

This study reports four new giant-planet microlensing detections from the 2024 KMTNet season, each revealing a planetary companion with mass ratios in $ (1.5\text{--}17.9)\times 10^{-3} $ around sub-solar hosts. Using 2L1S modeling with grid searches over $(s,q,\alpha)$ and downhill optimization, the authors identify distinct morphologies, including central caustics, asymmetries, dips, and caustic-crossings, and confront multiple degeneracies (close–wide and inner–outer). Bayesian analysis, constrained by angular Einstein radii where available, yields host masses in the $0.5$–$0.7\,M_\odot$ range and planet masses from roughly $0.8$ to $12\,M_J$, with distances placing systems in both the Galactic disk and bulge. The results underscore microlensing’s strength in detecting giant planets around low-mass hosts and at separations of a few au, enriching the planetary demographic picture beyond the snow line and supporting comprehensive, bias-aware population studies.

Abstract

In this work, we present analyses of four newly discovered planetary microlensing events from the 2024 KMTNet survey season: KMT-2024-BLG-0176, KMT-2024-BLG-0349, KMT-2024-BLG-1870, and KMT-2024-BLG-2087. In each case, the planetary nature was revealed through distinct types of anomalies in the lensing light curves: a positive bump near the peak for KMT-2024-BLG-0176, an asymmetric peak for KMT-2024-BLG-0349, a short-duration central dip for KMT-2024-BLG-1870, and a caustic-crossing feature for KMT-2024-BLG-2087. Detailed modeling of the light curves confirms that these anomalies are produced by planetary companions with planet-to-host mass ratios in the range of $(1.5\text{--}17.9)\times 10^{-3}$. Despite the diversity of signal morphologies, all planets detected in these events are giant planets with masses comparable to or exceeding that of Jupiter in the Solar System. Each planet orbits a host star less massive than the Sun, emphasizing the strength of microlensing in uncovering planetary systems around low-mass stellar hosts.

Four Giant Planets from 2024 KMTNet Microlensing Campaign

TL;DR

This study reports four new giant-planet microlensing detections from the 2024 KMTNet season, each revealing a planetary companion with mass ratios in around sub-solar hosts. Using 2L1S modeling with grid searches over and downhill optimization, the authors identify distinct morphologies, including central caustics, asymmetries, dips, and caustic-crossings, and confront multiple degeneracies (close–wide and inner–outer). Bayesian analysis, constrained by angular Einstein radii where available, yields host masses in the – range and planet masses from roughly to , with distances placing systems in both the Galactic disk and bulge. The results underscore microlensing’s strength in detecting giant planets around low-mass hosts and at separations of a few au, enriching the planetary demographic picture beyond the snow line and supporting comprehensive, bias-aware population studies.

Abstract

In this work, we present analyses of four newly discovered planetary microlensing events from the 2024 KMTNet survey season: KMT-2024-BLG-0176, KMT-2024-BLG-0349, KMT-2024-BLG-1870, and KMT-2024-BLG-2087. In each case, the planetary nature was revealed through distinct types of anomalies in the lensing light curves: a positive bump near the peak for KMT-2024-BLG-0176, an asymmetric peak for KMT-2024-BLG-0349, a short-duration central dip for KMT-2024-BLG-1870, and a caustic-crossing feature for KMT-2024-BLG-2087. Detailed modeling of the light curves confirms that these anomalies are produced by planetary companions with planet-to-host mass ratios in the range of . Despite the diversity of signal morphologies, all planets detected in these events are giant planets with masses comparable to or exceeding that of Jupiter in the Solar System. Each planet orbits a host star less massive than the Sun, emphasizing the strength of microlensing in uncovering planetary systems around low-mass stellar hosts.

Paper Structure

This paper contains 10 sections, 6 equations, 7 figures, 7 tables.

Table of Contents

  1. Introduction
  2. Discoveries and data
  3. Light curve analyses
  4. KMT-2024-BLG-0176
  5. KMT-2024-BLG-0349
  6. KMT-2024-BLG-1870
  7. KMT-2024-BLG-2087
  8. Source stars and Einstein radii
  9. Physical parameters
  10. Summary and conclusion

Figures (7)

  • Figure 1: Lensing light curve of KMT-2024-BLG-0176. The lower panel presents the full light curve of the event, while the upper panel provides a zoomed-in view around the peak. The solid curve corresponds to the best-fit 2L1S model (wide solution), and the dotted curve shows a 1L1S model derived by excluding the data affected by the anomaly. The two insets in the upper panel illustrate the lens system configurations for the close and wide solutions. In each diagram, the red cusped figure represents the caustic, and the arrowed line denotes the source trajectory. Coordinates are centered at the position of the primary lens and lengths are scaled to the Einstein radius.
  • Figure 2: Light curve of KMT-2024-BLG-0349. The notations follow those used in Fig. \ref{['fig:one']}.
  • Figure 3: Light curve of KMT-2024-BLG-1870.
  • Figure 4: Light curve of the lensing event KMT-2024-BLG-2087.
  • Figure 5: Locations of source and RGC centroid in the instrumental color-magnitude diagrams. The position of the blend is also indicated in green for events where the blend flux was measured.
  • ...and 2 more figures